500 hrs certainly isn't experienced....but what leads anyone to think the exact same things wouldn't have happened to this young man in almost any other aircraft?
Apart from (some of) the EFATO memory items being allegedly completed, and you have to ask why? (In cruise they would most likely make things worse), he appears to have sat there and done nothing meaningful.
By 'worse' I mean that pushing the props to full fine and then not feathering simply creates more drag - and maybe what led him to think the engines were producing 'some' power - Windmilling RPM being a product of airspeed and MP returning to somewhere close to ambient, say 22 inches at 8000'.
Mixtures to full rich would probably set him up for a 'too rich' condition if he suddenly remembered (he obviously didn't) to change tanks and flipped on boost pumps as well.
This pilot's actions seem to be a result of rote learning - he could peel off the EFATO memory items (inappropriately) while 'controlling' the aircraft but there was ZERO understanding...of what was happening to him or what happens in any engine failure in cruise vs one on takeoff.
A training issue?
Most likely. I don't think the guys 500 TT is the most important issue...it's what he didn't learn/wasn't taught in that 500 hrs.
Maybe he is one of those Gen Y who feel GA is a burden to be born for the least time possible and didn't WANT to learn his craft properly...maybe he's thick as pig****...or maybe he was just a victim of a deficient training system bereft of real experience/talent?