Rant time: What's Met policy on traffic stops.

I was riding through New Cross last night and in front of me was a Police BMW with two officers in it. In front of them was an Aprilia sports bike that was so loud that even with a crash helmet and earplugs it was painfull. This thing was absolutely deafening even at tickover. Its tiny number plate was hidden up under the seat and the rear lights were LEDs arranged to make it impossible to see the plate. The bike stopped at traffic lights and the police car stopped behind it. The passenger could have easily got out and pulled the guy over for a word even if he wasn't nicked. Instead we all sat there with our ears bleeding until the lights changed and it roared off. Now I hate to be "that guy". I know resources are super tight but come on. No wonder London is full of illegal bikes, scooters, up to goodness knows what when even low hanging fruit like this is ignored. Is this official policy or just two cops who couldn't be bothered with "trivia".

Edit: thanks for the insights. Lots of valid reasons why they didn't tell the guy not to be a dick. Individually it is trivial but London now feels like the wild west as far as traffic is concerned. Bikes and scooters without plates and home made 40mph+ electric bikes are the norm now. It all comes down to resources I guess. It's not like you've got nothing else to deal with.