Apparently he is threatening the company's right to free speech. They expressed an opinion that his tweet was false. He said they had no right to say so.
That's what is called a threat to curtail a company's right to say what it wishes by the Federal government.
On the other hand, a website has the right to make whatever rules it wishes to. The president has no free speech right in Twitterland. That is private property.
He is such a simpleton.