So just tested a theory out with a friend and it works. You are able to do this in co-op. However you can not finish the game in co-op. If you do the Weekly Challenge on Night Fall and try the glitch as soon as you get you and your buddies though the
door all but one of you has got to quit out of the game. If you do this the game well switch to solo allowing you to finish the Mission and complete the Weekly Challenge.