You do not understand. He would have felt like shit and gone through the same things whether everyone was mean to him or nice to him. People being nice when someone in this situation is experiencing problems is going to cause the same reaction as people being mean. Either stimuli is going to trigger already existing issues he was struggling with. He could have just as easily misread kindness as pandering bullshit and despaired as a result.
The kind of shit you're talking about is the sort of thing that makes normal people depressed and stupid teenagers cut their wrist. This is an entirely different beast.
I have been in his position, and still might be again, and I can tell you with certainty that people being mean to him had very little influence on his mental health other than to maybe present itself as the cause of something that was already occurring within him.