So like, I'm pretty darn sure Mo Xuanyu did not actually make a pass at Jin Guangyao.
For several reasons, like for one thing hitting on your own actual brother who is also your boss is genuinely insane behavior, in a way nothing else we know about the guy actually matches, other than his reputation for being crazy which mostly seems to originate from the same point as the sexual harassment allegations. which tracks because even with rampant societal homophobia, that's such a crazy thing to do people would question it if it didn't come paired with the information that he's insane.
Then there's the fact that if that had actually happened, there's basically no way master spin artist jgy would have let it get out, because actually experiencing that would trigger his sense-of-uncleanliness issues so hard.
But what we see is that somehow Everyone Knows that it happened, but also that Jin Guangyao totally didn't tell anyone, because he's too merciful and kind and respectable. It just mysteriously leaked somehow that this private scandal happened.
(Also, to step up a meta level, the gay goth kid who was never quite accepted into his own family and wound up self-destructing was in fact guilty of the homophobic allegations spread by the powerful man who manipulates reputation for personal advantage? This is not the kind of story where that would be true. The thematic dissonance is too much.)
The only way it's believable that mxy made a move on jgy is if jgy spent a long time maneuvering him into it, hinting and deniably flirting and just generally being maximum skeeze, just a huge elaborate incestuous honeypot, just to bait a 'ruined reputation' trap. Which makes no sense at all.
I don't think jgy is necessarily above that kind of creepy grooming behavior but I do think he would hate it, and definitely wouldn't resort to it when sowing rumors would work just as well. and expose him to less risk.
So Mo Xuanyu didn't do it.
So what we've got is that Jin Guangyao systematically obliterated this kid's credibility.
No one would listen to anything he said after being expelled in that sort of context, especially anything against Jin Guangyao, whom he now has obvious motive to smear. This was a preemptive strike against some kind of leak.
It's exactly the kind of thing jgy would do--it targets individual vulnerability, leverages the weak points in Mo Xuanyu's reputation into gaping chasms, in a way that associates jgy with scandal but makes him personally look better. also shows signs of jgy projecting his own issues onto others. The MO fits.
And his motive is easy to construct: Mo Xuanyu had had access to his secrets, such as Wei Wuxian's manuscripts and probably a lot of the other ugly shit. And Jin Guangyao needed him silenced, due to some thing or other, but as with SiSi didn't want to have to kill him.
(A fascinating thing about jgy as a villain is the moments where he yields to sentiment pretty consistently contribute to his destruction.)
But then we come around to: so why didn't Mo Xuanyu sic Wei Wuxian on Jin Guangyao, then?
In cql wwx does have a curse cut for jgy, to keep him in the plot and create an additional open storyline to resolve, since viewers are gonna be denied romantic catharsis, but in cql the homophobia plotline isn't there because all the gay is censored, and mxy allegedly hit on qin su instead. which is less utterly unhinged to do though still big wtf.
In the book, mxy summoned the Yiling Patriarch just to kill the Mos. (Which he didn't even do lmao.)
So I've always been sort of poking at that, like if you're destroying your own soul to get revenge, why spare the person who deliberately ruined your life?
Even if he had done the thing, it was weird! Maybe even weirder; if you're in a headspace where making sexual advances anyone should be able to predict are unwelcome seems like a good idea in the first place, there's a pretty good chance getting punished for them isn't going to make you think you were in the wrong. Otoh there is a zone where he could have done it, gotten the backlash, cleared his head a bit, realized it was fucked up to do, and therefore not held a grudge in that particular direction, but it's still weird. (And also he definitely didn't do the thing.)
But if he was so angry, why was he not angry at Jin Guangyao? Who definitely kicked him out of the Sect, all else aside?
And then I looked at the passage in Jin sect where we swap to Jin Ling's pov and he tells us one of the few first-hand things we hear about Mo Xuanyu: He thought Jin Guangyao was the most amazing person in the whole world. He adored him.
And being betrayed and rejected by him didn't turn that into resentment. Even though he resented the other side of his family enough to want them gratuitously murdered.
So you know what I think happened?
I think Mo Xuanyu thinks it was an honest misunderstanding. That Jin Guangyao, his idol, falsely concluded that his gay little brother was creeping on him based on a misinterpretation of his admiring behavior, and was appropriately revolted. And that Mo Xuanyu doesn't blame him for it. He blames himself.
He went back to his mother's family to rot genuinely feeling like the ruination of his life was his own fault for being creepy. And died like that.
Because of that, to a considerable extent. How can you bend any of your will to saving yourself, to getting out of an abusive situation and seeking a better one, when you don't think you deserve to be saved?