Cheshire Police have been taking a similar stance.
In both cases, there is some evidence that the incidents causing the reaction by the police were not races, but were more likely to be sportives. The public, of course, see cyclists with numbers on, and not unreasonably assume that a race is being held.
Personally, I believe that some sort of regulation/supervision/permission/notification is needed for sportives/charity rides etc if we are to protect our currently regulated events such as road races and time trials.
The "Wiggins effect" has been responsible for an explosion in cyclist numbers, it would be very cruel irony if it also killed off the very sport that started it.