At this particular moment in time, buffalo-ing this particular burglar solved this particular problem. Shooting would have been reasonably articulable, IMHO, but the grand jury and criminal court MAY have disagreed. While it is true that striking with a firearm is, legally, deadly force, it is normally better if nobody acquires any new deep holes during an incident, even if deadly force is justified. (I did put a hole through a human being, in the line of duty, and did face a hostile grand jury, even though my opponent had a bludgeon held high, and a knife chambered for a thrust.)
Did this officer make errors? Yes, he made tactical errors. At the one particular moment in time, however, his handgun was a contact weapon-of-opportunity, and became a tool to apply lethal force with a less-than-lethal result. (A head strike is, by definition, lethal force.)
Do I recommend buffalo-ing felons? No, of course not. Just saying it worked this once.