The fact that he was behaving like Ron Zimmerman, simply put.
He actually got banned TWICE from the Spidey ComicBoards - the first time, because literally NOBODY who was moderating the boards could believe that any professional comics creator could POSSIBLY be saying the amount of stupid shit that he was saying on their boards, to the point that they AUTOMATICALLY assumed that he was a troll impersonator.
After Marvel contacted them, though, and let them know that, no, actually, the guy behaving like 4chan on steroids, who offended and upset literally EVERY SINGLE PERSON who read his posts, was, in fact, Ron Zimmerman, they unbanned him ... but after a while, even with the standard message board practice of creators being the Some Animals Who Are More Equal Than Others, everybody finally had enough of his constant derailing and insulting and obscenities, and he got kicked out AGAIN.
Ron Zimmerman is the only creator who makes Chuck Austen look good. Based on his conduct on ComicBoards, he demonstrated absolutely no redeeming traits whatsoever, on any conceivable level. His behavior made the WORST flamewar you've ever seen on LJ look more intelligent than William F. Buckley and more civilized than ancient Greece and Rome.