No one is scapegoating mentally ill people by stating the fact that there is mental illness that can lead to dangerous and / or criminal behaviour. An estimated 30 to 70 % of all homicidal criminals have at least one mental illness.

It’s also not ableist because “mentally ill people” is not even close to a homogeneous group of people. There are thousands of different mental illnesses and more than 20 % of people in the USA are mentally ill.

No one is saying these people are all murderers.

Please stop trying to push this weird agenda of “some people are just born evil” or made evil or whatever it is you are trying to say. It’s a step forward to recognise how society can prevent criminal behaviour, for example by treating mental illness better. “Evil” does not exist. There is always a reason of why someone behaves the way they do.

"…political conservatism and motivated social cognition (Jost, Glaser, Kruglanski & Sulloway, “Political Conservatism as Motivated Social Cognition,” Psychological Bulletin). In a nutshell, the article—by Stanford and UC Berkeley researchers—seems to suggest that conservatism is a mild form of insanity. Here are the facts. A meta-analysis culled from 88 samples in 12 countries, and with an N of 22,818, revealed that “several psychological variables predicted political conservatism.” Which variables exactly? In order of predictive power: death anxiety, system instability, dogmatism/intolerance of ambiguity, closed-mindedness, low tolerance of uncertainty, high needs for order, structure, and closure, low integrative complexity, fear of threat and loss, and low self-esteem. The researchers conclude, a little chillingly, that “the core ideology of conservatism stresses resistance to change and a justification of inequality.” The above list of variables is more than a little unsavory. We are talking about someone full of fear, with a poor sense of self, and a lack of mental dexterity. " -above is an excerpt from Psychology today article

No, these people literally need medical intervention and they’d very likely be better, more compassionate, healthier people.

Mental illness is chemical imbalance, inherited conditions and unresolved trauma. Science has answers and therapies, but this group is socially conditioned to avoid addressing their metal health and our society fails (largely in a broken loop full of the same conservatives denying funding) in not making access to care undeniably available, affordable/free and encouraged.