I feel like this entire issue is about perspective. And everyone is right from the way they saw the situation.
KV is locked up in the house with no contact whatsover with the outside world. He meets Salman once a week, he teases him, its all part of the show, the show's over, it's forgotten for a week.
TJ is part of the audience, she sees it like we do and gets offended over how her husband is treated and decides to voice her opinion on social media. (Nothing wrong with this since open letters have become such a trend nowadays)
Salman brings up the issue to defend himself, because he got offended over the letter like anyone would, considering they are on good terms with him and his family outside. He wouldn't have even brought up the letter if it was for any other contestant. So what was wrong in him asking KV directly if he feels offended by his jokes?
KV, hearing and seeing only Salman's perspective feels bad for him and questions his wife. And when he spoke to the camera, he ALSO said that let me talk to TJ to clarify everything.. how come no one picked up on that?
I said this before and i'll say it again, kv isnt going to change who he is no matter what the situation. So we cant say he did right/ wrong and judge him for it. Nor can we blame TJ for writing that letter and Salman for bringing it up. Everyone did what they thought was right.