It's an odds thing. He was unlikely to win. There are some very strong opponents. Could he have won? Sure. But note that he didn't protest the dress code at the beginning of the event.
And sure, he's "fed up" with FIDE (in the sense that everyone who thinks they are bigger than a league does). So why did he participate? If he had the purported principles, he should just withdraw from FIDE sanctioned events, no?
He’s been fed up with FIDE for a while if you’ve been paying attention. There’s a lot more to this than just his pants.