Two days after supporters stormed the US Capitol on January 6, 2o21, Twitter permanently suspended Trump’s account. The decision was due to their “Glorification of Violence policy, which aims to prevent the glorification of violence that could inspire others to replicate violent acts,” drawing a direct connection between them and the Capitol riot and concern of further unrest.

Twitter CEO Jack Dorsey explained that, while he believed the decision to be right, was concerned about the precedent such a ban might create.

Twitter Blog – Permanent suspension of @realDonaldTrump
The New York Times – Inside Twitter’s Decision to Cut Off Trump
NPR – Jack Dorsey Says Trump’s Twitter Ban Was ‘Right Decision’ But Worries About Precedent
Business Insider – Twitter loses $5 billion in market value after Trump is permanently barred from the platform