An impossible threat to fix, for all the reasons discussed in the article and comments. The only disincentive you can rely on for somebody showing you a fake badge is the small comfort that it is a huge felony for the guy to do so, so he's either really a cop or willing to face some hard time. Either way, resisting is not a good idea.

Having a lawyer on retainer and speed dial might help you catch some of the BS and/or protect yourself, but most Americans can't afford that. A (supposed) cop can easily claim PC to prevent you from calling anybody else.