At every airshow I have participated in, there has been a comprehensive briefing for all pilots which has included many things, including the minimum altitude for the display. I have no idea what the limits were at this show. If it was lower than 200 feet we had to have a special clearance. Maybe he had it. If not, bad show!
Airshows are about pushing the limits beyond what is normal. I do not know what the limits were, so will not pass judgement. Do you know?