The cop didn't know what the hell he was doing.
Despite the blowjob from the newspaper, that's my opinion. Modern high-testosterone gunfight tactics the NE cops follow involve unloading on a perp to the point of damn' near bump-firing, which has led to things like an entirely innocent guy getting drilled 19 times by NYPD's finest. It's a ridiculously inappropriate tactic in a hostage shield situation.