I agree. You'd have to be quite a tool tell a cop that you are a fellow officer of the law and to cut you some slack. However, you can say you have your service weapon with you so he doesn't freak when/if he sees it, then when he asks you who you are with, tell him FFDO and let HIM decide if you are worthy.
It's almost as bad as the private pilot bragging to girls in the bar that he is a pilot, meanwhile an airline crew is sitting right next to him...