civilian truck driver with a cell phone!
and he blocked the rest area exit with his truck while the keystone kops were enroute. And Moose was probably still steaming about the leaked plate number.
Moose probably thought this also and reasoned that he had a better chance of cathing these two thugs if they didn't know that their plate number was known to the police.
I would have withheld the plate number also, and I'll tell you another thing; if this leak had resulted in the sniper's getting away again to commit more murders, the leaker would be on the griddle right now. He was lucky that things turned out the way they did.