Imho his wasn't the case at first. I think - but have no evidence - bungie countered the cave to some degree with this massive attack from all sides. There are even yellow enemies coming in those mass fight waves.
I really like this aspect and the possibility of the game to change such variables on the fly without patching.
I don't think this was a counter to the loot cave as I actually encountered the exact same thing in a different area in the beta, doing a farm route picking up chests. After about an hour suddenly things got crazy. I think it might be a rare recurring thing in any area where two factions are always fighting.