I know there was bad blood between them but she was still her sister.
And it's not really about what she said, but how she said it - in such a light-hearted, almost cheerful way.
And if it's so perfectly understandable that she hates Kristin and that she has no reason to forgive her even after she died, how do you explain the relationship between JR and Bobby, or JR and Sue Ellen for that matter?
Following your logic, they should have been dancing on his grave.
The only difference between Kristin and Sue Ellen was that Kristin actually pulled the trigger.
Regarding "The only difference between Kristin and Sue Ellen was that Kristin actually pulled the trigger": That's not true at all. Even if it were true, the difference between pulling the trigger and not is the difference between committing murder and not committing murder. That's huge! It's not the only difference though. Kristin framed Sue Ellen for murder - set Sue Ellen up for a prison term. You never do do that to family! You just don't and Sue Ellen never did it to Kristin which is a MAJOR difference between them despite what you claimed was their only difference.
Regarding "And if it's so perfectly understandable that she hates Kristin and that she has no reason to forgive her even after she died, how do you explain the relationship between JR and Bobby, or JR and Sue Ellen for that matter?" I explain the relationship between JR and Bobby as two brothers who were rivals and competitors but not enemies. JR and Bobby each have bad qualities that the other puts up with because they are brothers and because each brother also has good qualities. There are times when they're bad to each other but there are certain lines they never cross because despite their differences they love each other. A perfect example of lines they don't cross was illustrated when Bobby was blinded. John Ross asked JR why he didn't just take Ewing Oil away from Bobby while Bobby couldn't see." JR explained that there are certain things you just don't do to family and taking advantage of Bobby while he was blind was an example of one of those things you just don't do. JR then said to his son that if he followed his advice "you'll be able to live with yourself."
Finally: "Following your logic, they should have been dancing on his grave." No, not even close. Whether you're talking about a sibling relationship like Bobby and JR or Kristin and Sue Ellen, or a romantic relationship such as JR and Sue Ellen, you don't judge the person you're in that relationship with based solely on the worst one or two things that person ever did to you. A human being's worth is not based solely on the worst minute or two of his life! It's much more complex. People's lives and the relationships in their lives are made up of all the good and all the bad things they've done. All of a person's actions, the good, the bad, and the in between are what make up who they are. Anything less than taking everything into consideration would be to do them a great injustice.
I have no reason to believe Rove's "logic" was contrary to what I've just state, since those are universal truths and Rove certainly didn't say anything to make me believe he's for some reason an exception in the way he sees things. Rove's post gave us no reason to believe his "logic", would be to "Dance on a person's grave if they've ever done something bad to you and refuse to take into account all the good they've ever done you."
Take Sue Ellen and JR's relationship for example. Why should she be "dancing on his grave"? The only way of thinking I can see that would justify that is if she based JR's value to her solely on the worst things he ever did to her. She'd be dancing on his grave only if she ignored all the qualities JR had that she admired as well as ignored anything good JR ever did for her.
He hadn't been a saint but neither had she. At the end of season 11, Sue Ellen shot JR when he was unarmed! That's worse than anything JR ever did to her. Jr showed a surprising large capacity for forgiveness when he refused to press charges on Sue Ellen for attempted murder despite that everything indicated that had JR taken this matter to court, all the facts of the case would be in his favor. Sue Ellen and Nick Pearce had broken and entered into his home. They were both guilty of trespassing and refused t leave when JR asked them to leave. It was the that he pulled out a gun and again asked them to leave. Rather than comply, Pearce assaulted JR and managed to take the gun out of his hands in the process. JR then tried to retreat from Pearce - still attempting to avoid violence. However Pearce made avoiding violence impossible by relentlessly following JR all the way out onto the balcony. It was then that there struggle tragically ended in Pearce falling to his death over the side of the balcony. These are all facts. Sue Ellen had no case and had JR pressed charges, she would certainly have been given a prison sentence. JR even at that time, even while he lay in a hospital bed with three bullet holes in him showed he had the mercifulness and compassion to spare Sue Ellen of that prison sentence. He still cared for her too much to do that and even more significantly, he didn't press charges because he didn't want John Ross to have to deal with the pain and embarrassment he would surely face if his mother were sent to prison.
They had both cheated on each other. They had both at times tried to make the other miserable. Then there are the things they valued in each other. Sue Ellen valued JR being a wonderful father to John Ross. That was perhaps JR's best quality and she valued it greatly. JR was an excellent provider and he supported Sue Ellen in a tremendously high standard of living. He was never stingy with her regarding gifts and regarding her being able to buy anything she desired. Regarding romantic love, Sue Ellen and JR both believed there was a "magic" between them.. That certainly can't be ignored! That was the basis for the excitement of the pleasurable and meaningful times they shared together, and why Sue Ellen married JR again after divorcing him.
JR was also courageous wen he needed to be. He literally walked through fire and almost died trying to save Sue Ellen and John Ross in the Southfork fire Ray caused. JR again risked his life to save John Ross when he was kidnapped by B.D. Calhoun. JR was shot in the process. When JR believed Calhoun was going to shoot him, even then his only thought was unselfish! His only thought then was of John Ross because he said to Calhoun: "If you're going to kill me now at least don't let my son see his daddy die"! To attempt to argue that Kristin had equally good qualities as these or even anywhere close would be impossible.
In summary, while JR had serious flaws, he also had serious redeeming qualities. Those redeeming qualities and the good times he had shared with both Sue Ellen and Bobby mean that he had considerable value to both of them. Kristin had terrible flaws but had no redeeming qualities. Because of that, Kristin simply had very little value to Sue Ellen and the only thing that made her of any value whatsoever to Sue Ellen is they were related.