Lots of practical survival methods are illegal. Trapping is simply much more discreet and you are less likely to get caught doing it than you would be shooting at the wee beasties.

In a survival situation, I really couldn't care less what any animal rights activist thinks, so long as they stay the heck outta my business. If they should attempt to interfere with me, I will treat them like any other hostile competitor, and respond accordingly. I believe in that aspect, I am much better equipped than they are to determine the outcome.