As a cop, I would rather know even just the basics of using the knight stick or extending baton than be at the Gracie level of BJJ.
From what I've gathered from talking to officers, bjj allows them to control the suspect on the ground where they have taken them to be handcuffed, and it lets them do this in a way that doesn't "look bad". That means less threats of lawsuits.
But this is not a thread about bjj and police work. I also know police who train traditional jujutsu and other arts.