Just because he wrote it on twitter doesn’t mean it can’t be a crime: Trump is stupid and shameless so he often lied or gave unlawful orders on twitter or some other public forum. He believed that he was totally protected by the first amendment or executive privilege. Those rights are not absolute and if he gave it half a thought (or had half a brain) he would have realized that. Executive privilege (or Article II) does not allow a president to do anything he wants. And when speech is in furtherance of a crime like fraud it’s not protected. You’d think a snake oil fraudster like Trump would have been aware of that. Of course he’s gotten away with it his whole life so I suppose he assumed he always would.