What's your point? That anyone you label a "troll" should not be allowed to participate? Before you answer, keep in mind that there are probably people who would blithely label you as a troll,just because they don't agree with you (or you with them).
No, that anyone that *twitter* labels a troll should be. It's their fucking site, they can do what they want, and personally I think it's a good move to have rules about not dropping turds all over their property.