I just got banned from Twitter a couple days ago for the same reason: "platform manipulation and spam". I only occasionally tweet about college football and don't do anything illicit at all. All I can figure is I was banned simply because of the accounts I follow, which included @TrackerTrial among other "controversial" conservative-type political accounts.
It's not merely "conservative" accounts who have been banned. Plenty of anti-war activists, supporters of government transparency and general voices against the narrative set by the DC blob have been banned who were in no way, "conservative". You could ask Wikileaks supporters how they have been treated by Twitter, if you can find any of them that haven't been banned.
