These questions are harder than people think. Because of animosity to trump, there's a willingness to rush from 'trump called on people to go to the capitol' to 'some people who went to the capitol committed crimes up to murder' to mean 'trump ordered people to commit murder' and should be charged with murder.
But however much people want to say trump didn't seem to mind if they did, however much he seemed to embrace 'bad people' we don't like, including ones who wore offensive messages, however much it could be said he was reckless not to demand they refrain from violence, it's not quite the same as 'he ordered them to commit murder'.
Consider how a Democratic leader could call on supporters of BLM to 'resist', to protest, to show their strength, and then they have a rally and it turns violence and someone in the group kills someone - would we say the same about that Democratic leader being guilty of murder? It's not quite exactly the same, but it's not too different.
It does seem to me, that however much trump deserves to lose social media for years of abuse, which didn't happen, that the two tweets that DID get a lifetime ban are pretty dubious for doing so, and more an excuse to finally get around to doing it than really justifying it themselves.
For example, one of the two simply said he won't attend the inauguration; but Twitter said that that could be interpreted as encouraging violence at the inauguration. Huh? That's a very weak claim. That standard could be used to vilify almost any message.
Imagine Biden tweeting it's a good thing if trump doesn't attend, something he said, and that being interpreted as calling for violence against trump supporters at the inauguration so he gets a lifetime ban. Huh? So clearly it's a sort of 'ban trump just because we've turned on him, and are using an excuse' more than for the reason given of the specific tweets.
And it's 'ok' because so many of us are simply glad to see trump finally banned. But it sets a heck of a precedent.
And it doesn't make it look better that their silencing trump comes the same month that trump declared war on them by wanting their legal protections from being sued removed. It colors the action with companies attacking and silencing the president on their platforms if the president dares to challenge their power.
So, this isn't as clear as people might want. This isn't that much a surprise when trump is seen as getting away without accountability on the one hand, then people are more willing to see accountability from another method even if it's not quite justified. It's a little like people not being concerned if OJ's rights had been violated at his second trial, because we think he got off of murder charges at the first trial.