This is the dumbest argument I've read in a long time. Unless you have someone hell bent to take your life (which if they're that determined they'll find a way anyway), even a lowly pellet gun is going to be enough to deter 99.999% of home intruders, muggers, and such.
If I'm firing a .22 caliber at you your not going to keep advancing. Your going to panic like a dog with their tail on fire and scramble.