I really don't think people understand what is really going on here. No one is arguing against that there should be better working conditions for -everyone-. This is not something you need to think about. Unless you're an asshole, if the question is "should poor working conditions <anywhere> be improved?" the answer has to be yes. But saying that, and having an actual movement trying to enact change are two different things. Developers -should- fight for better working conditions. But there is no union, and even among developers they are split between wanting to voice their concerns and just keeping their heads down because they love their jobs more than their personal wellbeing.
Right now the SAG-AFTRA, an actual union, is fighting for the rights of their members. There is an actual movement trying to enact change for one group. No movement exists for the other in question here. Nolan North isn't going to start one. He isn't even a developer. He's just stating what is a known fact to everyone, that there should be better working conditions for everyone, but he stated it in a specific way intended to undermine the current movement by using their tag line and throwing it in their faces. He basically said "You know that Performance Matters thing that's going around lately? Fuck that, this OTHER group, their performance matter MORE! Eat that! Bbl, I got mine, fuck yours!"
It is in fact #AllLivesMatter deflection. It doesn't mean that all lives don't matter. Saying the performance of game developers matter more than voice actors when you know they are using that line to fight for better conditions, you are telling them "yo you're not that important."