“Your mother wears army boots.”
Somehow I don't think that would be described as obscene.
Gates had already called him a racist. This is a good interview if you have time to read it or watch the video.
The Cambridge police know what was said. That's why they are supporting their fellow officer.
I guess Sgt. Crowley had to make the report politically correct for the Cambridge police department.
I still remember an old episode of the TV show “Batman”. The Joker is taunting Batman and hurls the insult, “Your mother wears army boots!” Batman responds, “Yes she does. And she finds them quite comfortable!”