WHS' coaches are experienced enough to know each opponents' strength prior to kickoff. It is common knowledge that teams like Greer, Union, and some others have no or very few club players and are not (yet) competitive with schools loaded with club players. Going into such games, I would therefore expect the coaches to have all subs in the starting line up for 80 minutes and instruct all their players to use the weaker foot only. All of a sudden, you will see their own limitations.
Additional restrictions are not too difficult to think of (scoring off a header only, scoring from outside the 18yd box, playing numbers down, ...). Perhaps WHS was not confident enough that they could beat Greer under such circumstances?
Kudos to Greer for trying to keep a game going and not packing all 11 players in their 18yd box. YOU have our respect.