I agree a 22 rimfire is not an ideal defense round. NAA mini revolvers are not intended for that. They're mouse guns or pocket pistols, intended for backup use only or for those times when you can't carry anything else. The old saying, it beats throwin' rocks.
Of course, if you ever had to use the thing defensively, you'd probably want to put it up against the bad guy's ear, throat, heart or cajones. In other words, when you can't run and your better gun is in the house and you're desparate.
I've had two-- a Black Widow in 22 mag which was stolen and my present one, a 1 1/8" mini revolver in 22 lr. I really recommend the mini revolver in 22 lr. It's smaller and you really can carry it in your front pocket all day and not know it's there. Also you will shot the lr more than the mag. I will say one thing about the Black Widow, though. Dang thing sounds like a 9 mm when it goes off.