To be fair, if I had to go through life with the initials B.M., it might make me pretty unpleasant too.
Just as an aside, I've moderated a few forums in my day, and I always hated when trolls inevitably contended that moderation actions were due to intolerance of their opinions rather than inappropriateness of their actions, and the First Amendment protected their opinions.
This (and almost every other) forum is a privately owned space, much like someone's house. If the management here wanted to arbitrarily ban everyone who had the letter E in their name, they'd have every right to do that (even if it wouldn't be the smartest thing to do). The First Amendment only says that CONGRESS cannot limit Free Speech, not that one has the right to be on someone else's property regardless of the owner's wishes.
Bernie's 1st Amendment rights are demonstrably not infringed as he can still say whatever he wants elsewhere.
I know this isn't news to most of you, but it's a big Internet pet peeve of mine.