I can only find 1 real case study, and it is a very small one that has yet to be pier reviewed, that I know of. I mean, unless you are taking into account all those aggression case studies, that didn't survive pier review? Bigotry is a problem, period, full stop. Saying people who play video games have a statistical higher average of bigotry is... well ridiculous, unless you bring something that shows it is more of a problem statistically in the game consumer space. And honestly, I'd say the lack of inclusiveness is a fundamental issue in the industry(devs, pubs, press), and a systemic problem inside the publisher and development world, that gets promoted by the press.
I mean, unless you are willing to claim that gay/bi/black/women/and ect, are in any way represented in developer, publisher, or press houses, then you would have to say the issues are more structural in the industry, and not actually the consumers fault. This is even ignoring the demographic switches in consumers DESPITE the fact that the industry is much further behind then the consuming audience.
I mean
Christopher J. Ferguson of Texas A&M International University does a good job here at exposing issues with the previous aggressive research, that can be applied to the current mentality of the games and the consumers who buy them. Because bigotry is an issue in the real world and the internet in general, doesnt mean you dont try and do anything about it, that would be stupid. You have to figure out how to differentiate yourself as an industry, and the way you do that is diversity in employment. Something this industry severely lacks.
When you accuse an entire segment of having a systemic problem, more so then the current social pop culture, you need to have something of substance and that can be empirically pointed to, to show it is an issue with that group of people. And right now there is nothing of substance, that I can see, that shows that the issues of bigotry is more of an issue in the game consumer(in fact I'd argue the game consumer is less prone to bigotry from my personal experiences, compared to a lot of other hobbies).