I think Custard is over-reacting. Not everyone say hi back to me. I don't mind. It's not like you have to. People in this world just don't get it. People think they can got off on others when they shouldn't. It can be hard to deal with people sometimes, and that's just there nature.
As for the reason of the ban, maybe he might have been planning something, maybe he wasn't. People might not be as they look. In either way, we can't know for sure unless proof is given saying one way or another.