As an armchair economist who believes that everything DOES happen at the margins, we can't completely ignore this, so I'm at least somewhat sympathetic to the argument.
But what really kills the argument is looking at how our medical professionals have stepped up and responded to COVID-19, putting their lives on the line every day, with utterly inadequate gear. And still they serve.
Yes, if the police are less militarized and have more personal liability/responsibility, it will reduce the level of interest in the profession somewhat, but I think we have to not kid ourselves about the degree of such an impact.
This is before we get into whether we really even want "those people" (who are attracted to the militaristic side of policing) 'serving' our communities at all.
Just as anti-pursuit policies have swept the nation to reduce officer-involved carnage, we can reduce escalation of violence.