of course it doesn't, but would you really deny a dying person peace of mind in their last moments? it is only then that they (might) realise how they were in life, though too late, the apology would still be sincere.
I agree with this. But I think that the reason for people doing the opposite is because if someone is dead, they will never be able to defend themselves or justify what they did again. So it's considered respectful not to speak badly of the dead because of this. However, if they were truly a horrible person and everyone knew it, there's not much point.
Sometimes people who are dying act like an asshole just because they don't want the people around them to be depressed or something when they die. It's like in TFIOS, they don't want to be a grenade.
I agree, my great grandfather, or whatever the relationship was to me, was dying and I absolutely hate him because he molested my mom. My mom confided to her sister about it, after 40 years of keeping what happened to her a secret, and she didn't give a shit just because he was on his death bed. That wasn't right and it didn't change the fact that he was a horrible person. Just because you're dying doesn't make you a saint
You can feel bad that they're dying, but don't make them out to be a saint when they've been nothing but a dickbag.