Most CCW course (that require a live fire test) require a center fire gun, usually 380 cal or bigger. The safety issues between rim fire and center fire are the same. The main issue is reliability, as I described, and stopping power. Also, during a course, an instructor doesn't want to hold up the entire class because one person has a poorly chosen unreliable gun that keeps misfiring or jamming.
I have been instructing in firearms, including CCW for over 20 years.
“The main issue is reliability”
In my experience, 22 LR is very reliable FIRED FROM A REVOLVER. I honestly don’t remember ever having one NOT fire from my revolver. That includes using my little NAA derringer. From a semi-auto? Whole different ballgame.