The best part is that they could have avoided all of this by paying their QA more for fewer hours. The changes they'll likely be forced to make by a union are probably much more dramatic than what they could have quashed pro-union sentiment by simply introducing themselves. Put another way: As an engineer, I have a great salary, good stock options, and decent hours. I favor unions in principle but don't have a drive to force my company to set one up because I am not so poorly treated that I think I need it. Why not treat QA the same way?
The exploitative practices that some in tech - especially the games industry - are exposed to are a long-term bet that those people won't mind being exploited and won't be convinced they can do better. It's a shame that bet pays off as often as it does.