> Which... can reasonably read as encouragement (or incitement, or glorification) of violence toward people.
Do you not see how I could just as easily use your empty standard to ban tweets saying “A riot is the language of the unheard.” -- a quote I largely agree with? This quote explains rioting as a consequence of oppression. But if I was as easily triggered as you, I'd have it banned since it "can reasonably [be] read as encouragement (or incitement, or glorification) of [rioting]" a definitionally illegal act.
And frankly, your interpretation of the Trump tweet is not reasonable. The most reasonable, common-sense interpretation is one linking severe consequences to severe actions. Does the phrase "When you play with fire, you're going to get burned" glorify burning people?
> Twitter is a part of the marketplace of ideas, is it not?
In the standard notion of a marketplace, you let decentralized end-users gravitate toward things they like and avoid things they don't like. If Trump's speech is so offensive, then let END-USERS decide to block his content or barrage his comments with condemnation or vote him out of office. Instead, you're advocating for a major centralized "authority" to make the decisions about tweets that should and shouldn't be seen, whether or not they're popular with the end-users. Yes, if they disagree that strongly with the censorship, those end-users can leave the platform, but that's analogous to "well, if you don't like it, then you can just leave". If people like something, they're rather fight to keep it good than let other people "ruin" it.
> ...whether the unoppressed is a straight man or a person who can threaten others with violence without consequence...
Mobs breaking windows, lighting things on fire, and stealing is violence. It exposes people to tremendous danger and tremendous injustice. Saying that violence begets violence should hardly be a controversial idea. I certainly don't think Trump's tweets are helpful in anyway. I think they're incredibly tone deaf and unhelpful. But I'm not going to cry to Twitter or Facebook and demand it be blocked.