For God's sake, he is (was) the 777 Fleet Manager, with umpteen hours on this and similar types, who probably practised this many times in the simulator. The official Boeing pictures are superb, the fly-by was clearly fully in control.
This was a day or so after the LHR 777 crash, and I happen to know for a fact that he was expressing his confidence in the 777 to Boeing.
There are airliner fly-bys at air displays - this was another one. His mistake was that he didn't give himself written permission beforehand.