On the caliber note... Ya,.22 is small, but would you stand at arm distance and take a few .22 to the chest, neck, or head? I wouldnt. Plus most crime is based on how easy it is to commit. Most women are an easy target, but once they pull a gun, grandma isnt an easy target now.
I say .22lr is better than a kick or bite. If you want to test this then take some 6x6 and hit it till your blue in the face. Now shoot it with even .22lr promise you will think differently. (Except you Mr. Norris, you dont count)