Rifles are easier to shoot than pistols. Rifles have higher muzzle velocity than pistols-especially .22 rifles. Bullet expansion from the .22 lr (from a 16" barrel) is good, as is penetration. The muzzle energy from a .22 carbine is as good as (or better than) most pistol cartridges up to .38 special.
With reliable, tested ammunition a semi auto .22 carbine is a formidable weapon-especially in the hands of an experienced shooter. No gun is better suited for informal target shooting-which makes the user ultimately familiar and comfortable with the weapon. You don't need 25 or 50 round magazines, either.
I have built a couple of Marlin 60s with 16" barrels and shortened stocks for home defense over the years.