It may not be a cheat like pushing the Templar or skipping the Bridge encounter in Crota's End, but is definitely sketchy. I don't see how anyone could look at this and honestly believe that it is a legitimate strategy that would be endorsed by Bungie. This isn't a team that runs through the encounter with precision and then maxes their class potential for massive damage. This is a team that says "-blam!- the encounter, lets just shoot her like a Strike boss". If Bungie implements some sort of patch to the encounter that forces the team to split, then that is that. It is a 'cheese'. If it remains an option without interference from the team, then it is a viable strategy.