Actually yes he can. Impeding the flow of traffic is an offense in many states and the cop can pull you over for it. If you were dumb enough to be blocking a COP for miles instead of moving to the right to let them pass, then you deserved to get pulled over.
Cops are allowed to drive as fast as they want, so one of the safest ways to exceed the speed limit is to follow a cop. This ensures you won't get pulled over by said cop, since you are behind them, and it also prevents the problem you experienced where you blocked a cop. Never block a cop. This should be goddamned common sense.