If you watch the replay, you can see one of the 4 plastic clips break, Mask is still on and attached to his head, once realising he may have a chance to stop the play dead he forcefully throws his head forwards to throw the mask off. Since he removed it himself, and since it wasn't something hitting the mask and causing it to come off it should have been at least a delay of game penalty. There is no threat of player safety if the mask is still secured by 3 straps.
_____ASP______
current ski quiver:
park, all mtn 181 ON3P Kartel 98
park,all mtn: 181 Armada AR7
big mtn, pow: 185 Armada JJ