First the team and school have rules in order to compete.
Some kids sign an agreement to those rules in order to compete.
Secondly - if it would go past the team, conference/league, and state level of rules then it may go to the National rules committee or organization. If it becomes a legal battle - money is involved and lots of it. Many things could happen if the rules are not followed. The school administration could drop the program. The league may not let that team in the league. The state might not let the individual participate in the regional, sectional and state tournament. Does one vistor want to compromise the entire TEAMs' season. Or will the Team want to compromise its' season for a vistors beliefs. It could be a tough way to start a season with a distraction that may only be one or 2 years. I would tell your cousin that Abdul should think of others (teammates, coaches, admininstrators, etc.) as well as his own beliefs.