Assuming that you have a little extra time, there's only one response to a cabin crew threat to involve the police for your taking pictures. "That's fine, I'll be happy to wait right here until they arrive." It may be against AA rules, but it's not a crime; and police aren't going to arrest you for it. If you're subsequently delayed, a creative lawyer could then make a claim based on a false report to law enforcement, which, itself, is a crime in nearly all jurisdictions.