This ban seems to heavily take advantage of the current moment, as it's obvious that he has tweeted worse things in the past. It's strange that they picked such a poor way to justify the ban when they could have made a significantly stronger case, and in doing so could have convinced millions more people that they are trying their best to apply policies evenly. For example, I have a hard time imagining why they chose…
I think the logic isn't that hard. Person says bad things to whip up a mob - Twitter unsure to take him seriously or literally. Mob actually materializes and several people die - Twitter sure they now have to take him literally
Trump is the ONLY reason I'm on Twitter. There is literally no other benefit I gain from being on Twitter. Also, people only ever respond to me if I tweet against Trump's policies. If I say anything about science or tech or humanity or art or say some interesting ideas, nobody listens to me. Nobody retweets me. Nobody follows me. It's like talking to a wall.
His term is over, and my reason to be on Twitter is over.
So from Twitter's standpoint they don't have much to lose by doing the right thing and banning him with only a little more than a week left.
If they had banned him 2 years ago they'd have lost 2 years of my ad revenue.