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.
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?
Changing organizations like FIDE doesn't happen by withdrawing.