This is laughable. It's our freedom of speech to alert others to DUI checkpoints, speed traps, or coupons at at the donut shop. Whatever we want. It's the same as flash the brights, which the police have tried (and failed) to stop [1]. I hope the NYPD does try to push this so they can get smacked down in court.
[1] https://www.washingtonpost.com/news/volokh-conspiracy/wp/201...