The answer is to educate yourself on the laws and protect yourself accordingly. In the OPs case, the owners, while most likely genuine people, should have known they needed permits and gotten them accordingly; they have no one to blame but themselves. In a society that is increasingly making it illegal/requiring a permit to own things as common as pit bulls, people need to be aware that there are laws out there targeting the animals they care for. The hysteria after the fact is disappointing, but at the end of the day is irrelevant; if you are legally able to keep your pets, let your neighbors cry all they want.

Now if it is legal to own your snakes, and some one like AC tries to take your snakes, call the cops! That's what they're there for. Just make sure you have any documentation on hand like the ordinances printed out on the subject, etc, to back yourself up for when AC inevitably tries to label your snake as something it isn't.

Best thing to do in this situation is to just stay calm and be prepared for the worst. Most people wouldn't have to deal with something like this, but I can see breeders finding this an issue.