This is an unfortunate situation where largely things worked the way they were supposed to. Somebody raised a stink. The administration took time to investigate it. Found nothing and within 3 weeks dismissed the complaints. It sucks, but sometimes shit happens. Especially in academia.
The problem appears to be that the 3 week suspension led to the professor’s income from unrelated work being affected. I highly doubt that this lawsuit will succeed. This is the process everyone in academia (and if they are lucky in private companies as well...private companies don’t even promise an investigation...their at will contracts mean they can simply terminate your position) agrees to and it works well, as it did in this case.
The issue lies with the private companies the professor makes money from outside the university, who he has at will and temporary contracts with, which allow him to be terminated for no reason.
Of course, the irony is that contrary to the professor’s claims, the entity he is suing completely protected him. It’s the at will contracts with the private companies that are the cause of his loss of income.
If UCLA operated like a private company he wouldn’t have had a suspension with an investigation. His contract would simply have been terminated.