I think career destroying 'accusations' should come with a hefty burden of proof, or the claimant making the accusations should be open to a serious defamation lawsuit. If he doesn't pursue a lawsuit then he's guilty as far as I'm concerned. He has the money to get a good lawyer. If he sues her for damages then the doubt persists and he can absolve himself, because he can win, he has absolute proof his career has been wrecked by nasty, baseless allegations. That's all they are for now.
It's not going to be as simple as that though. Who wants to sue their ex-gf? I didn't want to sue my ex-fwb-whatever and I ended up not going through with it since it wouldn't have accomplished anything positive. All the real damage was done by the irresponsible press, angry self-righteous people, and me for not handling the crisis situation well, and it had long since finished playing out by the time I had to finalize the decision to sue or not. Regarding my situation: it's fucked up to sue a person with psych problems for expressing their psych problems IMO. That's part of what made the whole thing so difficult to process properly; it was peak #metoo witch hunt season, people posted screenshots of it after she had already deleted it from Facebook on her own (and it was posted on her Facebook to her Facebook friends, not to the press), people on the mod team leaked what I said in private under NDA that wasn't meant for the public, and I didn't know what the hell was the ethically correct thing to do in that situation from that point, and no one else did either, so I kept rewriting my statement (about 12 different times) but not publishing it.
Everyone took that as even more of a presumption of guilt, but it wasn't me having nothing to say. My initial response to the mod team in private (which got leaked to varying degrees) was honest and flatly denied it, but the next day her Facebook thing was deleted and it hadn't turned into a scandal, so it was ambiguous from that point on. It was emotionally difficult to see all the things that transpired as a result of the scandal that followed through regardless of that, but the only way I could see to exonerate myself in an ethical and responsible was to proceed with a legal defense in private without looking for damages. There's no way I was going to publish a bunch of personal stuff involving other people to an angry mob. I will not do something like that and fuck anyone for trying to compel me to. I handled it in private, but damages and retractions are how defamation lawsuits are resolved, and per state law according to my counsel, the statement being retracted already only left seeking monetary damages, so filing the suit was senseless.
Things are rarely as black and white as they look, and basing things on whether a suit is filed or not is definitely not how to straightforwardly solve for it.