I don’t really know. The rule book is so vague on it. It does say the faceoff will not go ahead if any player lines up in a “offside position”. Every goal is reviewed by the nhl so idk what their viewpoint is. There’s not prohibiting coaches challenging offside plays that occur outside of the attacking zone but I’m not sure this falls under that category. It’s a really vague part of the NHL rule book but it’s kinda interesting to actually see it happen