The problem is that you won't know whether it is fake or real authority until you run afoul of someone who has real authority and is annoyed enough to actually assert it. In addition to the federal laws that we all know and love, airports are subject to any number of ordinances and other local regulations that are near impossible to locate ahead of time (and some of which may be covered in the airport's security program which is by definition sensitive security information and not accessible to the public). What might be legal (but dick-ish) at one airport may be against the law at another.