I watched that barrel roll on youtube today. He got really low near the water and barely recovered. That being said, how many trained pilots would even attempt a barrel roll in a twin turboprop passenger-hauler let alone able to complete one, pretty or not, and keep control? He claimed to just be a gamer. The audio between him and ATC was really weird. Seemed very calm. Rich showed no fear or panic at all. Very incongruous.
Q
Depends if you care about the aircraft and/or your career. I have no doubt that anyone who has done any aerobatics ever could do it easily. Barrel rolls are taught to and then executed by students with around 70 hours total time (TT). In the vid in #279 I'd wager less time than that.