This "idea" ... HackGagAckPhft! ... was floated locally a few years back. From our perspective it is clearly a terrible idea to force an officer to retirement after one, two, or however many shootings.
Unfortunately, it is getting traction in some places. The guy I shared a table with during the week long ForceScience class was being forcibly retired by his agency in his late 30s. He'd had six or seven shootings, ALL cleared and legally/morally/ethically justified, in both patrol & SWAT. New chief came in & he got retired.
Verified word is that deputies at one large west coast special enforcement bureau are getting bounced off special weapons teams after 3-4 shootings. For guys at the pinnacle of their career, that might as well be retirement.
Someone somewhere is pushing the idea of ruining guys & gals through back channels. No doubt that'll impact working cops and deter them that much more.