Mojo POH emerg actions for engine failure during climb...
1.airspeed 101kts
2.directional control, maintain
3.power op engine, max continuous
4.inop engine, identify and verify
5.inop engine, complete engine securing procedure.
Land as soon as possible at nearest suitable airport.
Actions for engine roughness...
1.emerg fuel pumps on
2.engine instruments, scan for cause
3.mixture, adjust as required
4.alternate air, on
5.cowl flaps, adjust for proper CHT
6.magnetos, check
He appears to have actioned as per the POH for failure in climb. Just possibly not the correct airspeed and descended. Might have also been a different story if he didnt have 900 (650kg) odd litres of fuel on board.
They are an awsome ifr aircraft to fly normal ops, but Im not confident they will not maintain height at mtow 1 inop. They feel and perform a little differently to the chieftain.