How about instead of pointing at theoretical repressed homosexuality (seriously?), spectrum disorder, steroid abuse, being half-Asian (seriously?), or affluence, we blame (for once!) masculinity? Specifically, toxic masculinity in which entitlement over women is closely connected to criminal, anti-social behavior like stalking, harassment, domestic violence, rape, and murder? Toxic masculinity that is pervasive in our culture, economy, and politics?
As far as I know, misogyny still has not been classified as a mental illness. Doing so would mean a huge chunk of our population would have to be declared mentally ill.
Men turning to violence because they think women have wronged them is terribly common. Just as common is this violence being minimized and excused by being degendered.
It’s just so convenient that people will immediately find a way to blame already marginalized groups like the mentally ill and queer folks for a heinous act that was committed by someone acting out a type of violence that is specific to straight men.
This rampage was quite explicitly enabled by a culture that conflates masculinity and sex with power, control, and dominance of women. PUAs and MRAs (as well as abusers and rapists) are just the more obvious, extreme examples of this attitude. But the notion that women simply owe men (their bodies, their time, their attention, their care, their labor…) is the water we all swim in, the air we all breathe.