Who has been protecting Chuck?

I have to wonder if Twitter has been slow to ban him because he is on a federal watch list and they are only now realizing that the threat is minimal to non-existent?
Internet chatter is often useful to law enforcement and the intelligence community. Obviously, neo-nazis, terrorist sympathizers, and kooks in general are aware of this kind of surveillance, to the point of paranoia. Even so, they are so stupid and so blinded by their ideology that they will often post material that is very useful to those who know how to distinguish a real threat from a free-lance doofus.
There may therefore be a certain reluctance to ban them so long as any possibility exists that useful data could be culled from their rants.