Okay, so some people take the bible very literally. Most other people do not. A lot of meaning has been lost through translation as well as through the changing of times, and a vast number of people recognise this. Even if we're taking the bible literally then either way Brandon could be construed as going against the bible, either as a woman who's cut her hair, or as a man who has longer hair. He has to choose whether to take the meaning which improves his life and health, or the meaning which will appease his mother. Seeing as his mother isn't God, or knows the ins and outs of God's teachings or thinkings, then it's down to Brandon whether he cuts his hair or not.