I saw mc chris at Dada in Dallas a few years ago. Some guy was jeering the opening act (Piebald, I think?) and mc chris called the guy out and had him removed from the venue. I wholeheartedly agreed with that decision. Purchasing a ticket to a show does not give you the right to be a disruptive ass.
This is different, though. Tweeting is not being disruptive. Even if you blast expletives, hyperbole, and all-out lies into your feed, you're not detracting from the collective experience of anyone else attending.
Billed as a "nerd rapper", I'm sure that mc feels very strongly about bullying and people picking on his friends. Sticking up for your amigos is a good thing, but this is a terrific example of a good intention going way too far.