Well, a bunch of venues threatened to not let him play... which I'm pretty sure he could've spun into a PR boost by making a public statement about it, just like all his supporting acts did. Even for those parts of his audience that doesn't care about politics, him calling out the venue owners might direct the backlash at them instead. Hell, maybe other bands would make statements about not playing at those venues too. It would have been a bold move, but he can take the financial hit, and there's a chance at least some venues might have backed down. It would have been the right thing to do.

Like you say, he wouldn't even have to make a statement on genocide directly, just about freedom of speech, artistic expression or something along those lines. There have been other recent instances of artists either cancelling shows in solidarity or using the stage for a statement in support of their fellows. Even this kind of "middle of the road" take would've been better, and probably smarter too. Setting the precedent that venue owners can push him around can't possibly be a sensible idea.