Homespun
With your persistent belief about some height loss being inevitable in the event of an engine failure, it seems you might not understand the mechanics involved. If an engine failed in this AS355NP, height loss will not occur if the collective is not lowered - providing the remaining engine can produce enough power to maintain rotor rpm. And as others have said, it is very likely that it was operating at a weight that would allow this. So, if an engine failed and the pilot does nothing, all that would happen is that the other engine would double its previous power output to maintain the main rotor thrust. Now how long that much higher output can be maintained for is another matter, but it would typically be at least 10 seconds, which would give enough time for it to move away and gain airspeed to enable the collective to be lowered and the aircraft fly away.