Really not sure what it is you are contemplating here. No one has been accused of a crime. There is no "legal process". There is no "proper, legal channel". There's not even an HR process, as no one involved is an employee of DC or Marvel. There are no "real criminals". There is no crime to be proven and no forum is which anyone would be found guilty. Various people have come forward and accused Ellis and Stewart, among others, or scummy behavior. Ellis more or less admitted to it.
The dangers of Trial by Twitter are fairly obvious, but the over-the-top hyperbole of some (e.g. the folks conflating this with "sexual abuse" or "grooming") are ultimately meaningless. If anything that was said about these folks is untrue, that likely will come out. If not - well, again, there's no crime. It's behavior that people (and companies) can decide how to feel about - but at least in Ellis' case, it is behavior that he has acknowledged and to which he has admitted. There's no need to clutch the pearls for him or his career - he will be fine.
And I think the empirical evidence is pretty clear that these types of allegations are very rarely made-up, especially when a plethora of "accusers" are telling the exact same story. For whatever that's worth.
Edit: Also - libel is a civil action, not criminal. No one will ever be "found guilty" of committing libel or be punished criminally for it.