The forever rhetorical question. Can a .22LR be used for self defense needs?
There's no doubt a rimfire can kill just about anything. A sane and rational person will stop at the sight and sound of a .22LR, and especially after being shot by one. But when adrenaline and/or drugs are involved, a person can absorb tremendous damage before being stopped. Until a person bleeds out, completely runs out of oxygen, or the central nervous system is incapacitated, a person otherwise fueled by the aforementioned adrenaline or drugs, can continue to fight and inflict harm on a victim.
I have shot animals with center fire rifle cartridges, and the animals continue to have enough stamina to run great distances, seeming to be unaffected until the final collapse. Other animals, hit the same way by the same cartridges, have dropped in their tracks. All of them hit in the head or cervical spine stop immediately.
That's the crux of the .22LR. Unless you disrupt the central nervous system, there are no other guarantees of immediately stopping an assailant. The same could be said of center fire cartridges, but the chances are much higher of inflicting enough damage to hasten neutralizing the threat.
Another thing. Anybody that shoots .22 LR regularly will recall episodes of misfires. I cannot recall the last time I've had a misfire with any center fire cartridge.
All that said, I would greatly prefer to carry a rimfire handgun than no handgun at all.