If he used JR servos they have been reports of locking at full deflection
Extreme Yak 54, basically went into a dive from 75ft---locked up or fail-safed or whatever these do. Pilot very skilled 3D etc, no dumb thumbs here. Not much left, at least $1000 loss. Batteries, switch, connectors all appeared healthy
If he used JR servos they have been reports of locking at full deflection so maybe not the reciever.
I still believe its hype when they say "immune" to rf....I would say "better"
Best to not get complacent.
Still its a good system and I have purchased more recievers and use an old stick to flight test them before putting in my 35%