The "toxic masculinity" thing is another major reason to be upset. I mean, imagine somebody blaming pedophilia on "toxic homosexuality". Fact is, most men don't commit mass shootings.
You're just catching at straws at this point. But hey, look, I can do this too! You said that blaming school shootings on men is comparable to blaming pedophilia on homosexuals. But the fact is that an overwhelming majority of school shooters ARE male, while most child molesters are not homosexual. Therefore, you are a homophobe for making this comparison. See how fucking stupid it was?
I feel like I'm stating the obvious but... when Saarkesian addresses "toxic ideas of masculinity", she is not blaming maleness in itself, but cultural constructs around it that she qualifies as "toxic". Your comparison implies that she holds senseless, largely unprovoked killing sprees as something inherent to the nature of men, when in fact she's stating the exact opposite.
Heck, the entire point of her "Tropes vs. Women" series is to point out what she sees as the expression of "toxic ideas of femininity" in video games.
It's toxic gun culture, not toxic masculinity (though the two can overlap in theory).
School massacres are not limited to shootings.