No. The First Amendment generally applies only to governmental misconduct.
Twitter and Facebook are private companies. They have their own First Amendment right not to be associated with Trump. And they have the right to set their own terms of service, and to hold violators of the terms of service accountable.
Even if Twitter and Facebook were governments subject to the First Amendment, incitement to riot and commit violence—which Trump is caught on video engaging in—is not First Amendment–protected conduct. U.S. Supreme Court case law has long held that such activity is an exception to the protections of free speech.
