You do have a point. I mean, if players can run other exotic armor pieces in there, why can't they be allowed to use their exotic helmets? If a player has been building their guardian up around a particular exotic helmet and you're not allowed to use it, that might impact that player's fun during the activity. Perhaps they could tweak the rewards if you choose not to use the mask next time in some way. Maybe they can reduce the amount of candy you'd get at the end if you don't have a mask on at some point in the activity, but add more rewards tied to completing certain branches. Maybe make the branch rewards a different type of candy/currency that you spend on something else or something. The current candy can be obtained everywhere else in the game right now anyways. The branch rewards could be something you can only get there and it could be something you can get without a mask.