Cops are just as*holes sometimes...someone gets a power trip and runs with it.
Similar story happened to my and my wife when we were on our motorcycles. We have those flasher/modulators on our headlights so they switch hi/lo beam constantly (for safety) and just riding along a highway some state trooper pulled us over and said, they were for emergency vehicles only. He even pulled out his TN law book and showed me the passage which read (paraphrasing here) "emergency and police vehicles are only permitted to use RED OR BLUE flashing lights and only under emergency situations". It didn't say anything about using your regular headlight...so we got a $500 dollar ticket (2 counts $250 each) and went to court. Ended up beating it costing us $250 for a lawyer and a wasted day at court...just because someone wanted to be an as*hole.
I'm sure you guys have seen a bike with a flashing headlight... that's exactly the point - YOU SEEN the bike and didn't pull out in front of him.
I'm so glad TN doesn't have a front plate rule...