Hate hearing this but at least he was not hurt. It could have been far worse. Obviously there was no intent to hand prop start. I have some experience with a J3 no starter. Decades ago a plane parked next to mine killed the pilot who tried to solo hand prop his plane. I was not there, and the pilot was not found for some time, because no one was around.
Personally would not intentionally hand-prop start larger higher compression engine, especially a trike. We all have turned the prop by hand for one reason or another. Like a Gun consider it loaded always. My Piper had a battery plug on the fuselage so you could charge and jump the plane behind the wing. That is something builders may want to consider.
This is a pretty good how to hand prop video. Seems like everything I have been taught: https://www.youtube.com/watch?v=qCqPtqvU9mg (he says something funny at 8:53)
__________________