I respectfully disagree with Pennyk and GG-1. Yes we are helping to "break the rules", but the same can be said about encouraging someone to drive 26 mph in a 25 mph zone! It's not like she was tying to bring a lion or tiger on board. I bet if you looked in everyone's carry-on, I think you will find someone with contraband. Why do Police dogs sometimes walk thru the train. Maybe they are looking for turtles or cans of beer not sold by Amtrak, but my guess is they are more likely searching for drugs!
Encouraging this individual to break the rules is irresponsible, IMHO.
Judging by grammar and syntax, this seems (to me) to be a tween-ish individual who REALLY REALLY REALLY wants to bring her turtle on her trip, rather than bear the thought of being away from the turtle for a week or two while a friend/relative cares for it.
Firstly, it's a good growth experience for such individuals to experience some separation and grow from the experience.
Secondly, if a hard-ass employee finds the turtle, and decides to enforce the existing policy, the individual will be faced with a NUMBER of unattractive alternatives (unboarding with the animal with some or all of her family, costing hundreds of dollars they may not be able to afford, or abandoning said animal, etc), all because she couldn't BEAR the thought of being away from pokey poo for a week.
Responsibility... pass it on.