We all deal with mental health challenges and we all live in a violent US culture.
And this is why it is vital to be honest about the mental health issues and illness that contribute these episodes of violence. I get what you are saying, there is a bias in the way these episodes are reported which affects the way people perceive and apply culpability. That’s a problem that disproportionately benefits white murderers and harms black murderers. To be clear, I think mental health is a factor in a lot of violent crime (most non money motivated violent crime?) and I think being more honest about that every time will help prevent events in the future. I don’t think that being more restrictive in how we apply the phrase is the answer.