Option 2

If Shaggy couldn't be a goalie and "backup goalie sitting on the bench" isn't a possibility either, he would most likely play defense. Defensive defense. His regular job is to prevent players from the other team from scoring on his own net and defense is what comes closest to that. Hang around the net, block shots here and there, keep opposing players away from the goalie - those things, definitely not being too much at the other end of the ice and score goals or - even worse take faceoffs. Of course defense happens at both sides of the ice and every player should defend, but it's still different from a forward. Assists are fine too. In general Shaggy likes the position he plays, otherwise he wouldn't have picked that as his main job, so if there really was no other option but to play as a regular skater it would most definitely be a defensive position since it's just more natural.