I'm a bit surprised that this fight with the POTUS doesn't have a stronger influence on Twitter's stock value.
He's not moving anywhere and any Twitter controversy gets more people to tweet about that controversy... Until he forces a significant part of his followers to leave, it's not a bad situation for Twitter to be in.
The risk isn't users leaving, it is regulation
So far every legal analysis of the order draft I've seen is "it's not enforcible, mentioned agencies fought not to regulate things like that, looks like it was written just to appease him". Once the regulation is realistic, (likely needing senate involvement) Twitter may be worried.