It sounds like several things could have happened with this guy.
- He totally put on a fake image during rush and ended up with a group he doesn't fit.
- The group he joined is desperate for members and pledged anyone with a penis.
- He expected it to be more like his friend's/bio brother's fraternity experience at a completely different kind of campus.
Ask him that if he's that unhappy with his fraternity, has he done anything to try to change it or thought of dropping out instead of constantly complaining. If he just kind of hems and haws and doesn't give you an answer, then just drop it.
The same with anyone else who's unsupportive. Just say "thanks for your opinion, but I'm going to go through it and check it out for myself. I would rather do that than wonder about it. If I don't like it, I can always drop out." Then CHANGE the subject.
p.s. thanks for the quote.