Different standards should and do apply in criminal trials ("innocent until proven guilty", "beyond a reasonable doubt"), civil trials ("preponderance of the evidence"), and the workplace, where anything goes.
I am saying employment is at will (in most US tech contracts) and an employer can terminate your contract for any reason. "Anything goes" = there's no set standards of proof
IANAL but my understanding is that employer can terminate you for no reason (as in not giving a reason). But if an employer fires you for cause and that cause is unfounded they can be sued for wrongful termination.
This handy list suggests you have a claim if you report you were harassed and your company fires you (retaliation), but not if you are fired after someone falsely accuses you of harassment.
