https://en.wikipedia.org/wiki/FEMA_camps_conspiracy_theory
https://en.wikipedia.org/wiki/White_genocide_conspiracy_theo...
Even president 45 fell for this admittedly pathetic troll:
http://edition.cnn.com/2016/01/22/politics/donald-trump-retw...
It does seem like there are a fair bit of analysts in United States intelligence (Clint Watts being on that side of the fence, essentially) who strongly believe that RT or Sputnik are less media sources, and are instead funnels of disinformation propaganda designed to destabilize the United States government. Whatever your personal opinion of these media sources are, in this light, Twitter's action here is hardly surprising.