I can tell you that if that scenario happened in real life, the victim's family COULD sue and would probably win. Unfortunately the criminals seem to have more rights than the victims. Take for instance a more realistic scenario...a robber breaks into a home and wakes up a family. He runs out of the house and across the yard and the husband shoots him.
The husband was protecting his family, right? Wrong! The robbers family sues and WINS because the husband used lethal means when his family was in no immediate danger. Had he shot him when he was in the house coming after him, it would have been legal. But killing someone running away from you is considered illegal.
Just my two cents. I do agree though that the mother is very much in the wrong, but having thought about it for a bit - the owner of the snake most likely said the snake was very friendly and perfectly tame, thus creating a false sense of security. The vast majority of the public knows little about snakes and while most are afraid of them, if someone who seems knowledgeable about snakes says her kid is safe holding one, why would she say no? Common sense should kick in (small kid, big snake...bad idea), but her ignorance of the situation shouldn't make her at fault.
IMHO, the snake should never have been in the store in the first place. One can't walk into a petstore with a tiger on a leash, why a 10 foot snake? This is not to say the store is at fault though. Upon entering the store, the mother knew people could bring their pets in there so she should have watched her kid closer.
The area of town this was in also contributed to this problem - it wasn't the greatest part of town and most of the people down there have "aggressive" animals - big dogs, big snakes, and so forth. That location of uncle bills is very commonly known to sell huge snakes. It's a status thing.