See their statement on it below. Inciting violence against others is against their ToS, and his comments about marching on the capitol building were interpreted

See their statement on it below. Inciting violence against others is against their ToS, and his comments about marching on the capitol building were interpreted by the team responsible for banning accounts that break ToS (presumably a specialist committee with it being Trump) as a violation: https://blog.twitter.com/en_us/topics/company/2020/suspension https://blog.twitter.com/en_us/topics/company/2020/suspensio...