I agree entirely with your point. I think, however, that there's something of a false equivalence: It is not the case that the tweets which are inciting violence are coming from all political believers in equal share.

We don't get "longstanding liberal principles" by publishing our speech on a private corporate platform. Freedom of speech and due process are merits of the law and not of Twitter's terms of service. Twitter is free to ban all incitements to violence without banning all hyperbolic political speech.