The due process thingy is a specific feature relating to the rights of the accused in formal judicial hearings or court cases. If one ordinary citizen wants to make an accusation against someone else outside of a formal judicial process (whether the accusation is demonstrably true or false), the accuser is under no obligation to wait until the accused has had a chance to defend him/herself.

There are a few cases in which formal assault charges have been brought against Trump, and to the best of my knowledge, no one abridged the due process thingy in these instances.

If someone accuses someone else falsely outside of the judicial process, then the accused one can sue the accuser for libel or slander or defamation of character. Since this suit would be a formal judicial process, then the initial accuser (the defendant in the lawsuit) would be afforded due process, not the initial accused person (the plaintiff).

99% of the time, when someone brings up the due process thingy in an online discussion, the purpose is not to protect some abstract principle of presumed innocence, but to stifle the accusations being made against someone the due process thingy defender likes.