Why are his beliefs dismissed? He's a home-schooled Christian son of a minister, he's most likely very passionate about his beliefs. Sure, he could of used them as a cop-out and it's very likely that he did, but it's still funny that everyone assumes that he was 'scared' of losing to her. He's the only one who knows what his reason is, and he's only a 14 year old kid.
In the end, the choice doesn't effect anyone but himself, she got to go on and compete and he had his choice to sit out. Dude was 35-4 anyway, he would of destroyed her, just as she was beaten twice and promptly knocked out of the tournament right afterwards.