Twitter & Facebook were waiting for the perfect storm:
1. Their decision had to have good optics—the company had to appear, to the public, that it was doing the right thing.
2. Their decision had to be consistent—the relevant policies had to be written down and enacted long in advance.
3. Their decision had to have the right timing, politically.
I’m also sure that there’s a massive stack of CYA documentation that these companies can produce on a moment’s notice. It’ll be interesting to watch the court case, because I’m interested in seeing what kind of CYA documentation these companies produce. They knew that Trump is eager to litigate. They knew this lawsuit was coming, and they were preparing for it long before they banned him.