Twitter bans or downgrades people for political reasons all the time. An example of twitter's pettiness; some time before they banned Breitbart's Milo for trolling, they removed the "verified" tag from his account. There is no sensible justification for this except that twitter was trying to hurt his credibility/give him a hard time. Regardless of what you think of Milo, that's just silly. Twitter is not at all conservative with (shadow)banning or other trickery. They'll even suppress trending tags that they don't agree with politically.