"It just feels wrong" isn't a valid basis for morality. Lots of people say the idea of someone being gay just feels wrong. Lots of people say people being non-Muslim just feels wrong.

Oh, I agree that it's creepy and something that could very easily be abused. But in this case, it seems to have been the right move. Whether the dead brother would have approved, we'll never know. But the living sister seemed to earnestly believe he would have, and that's enough for me.