legally, the muslims were out of line. morally, they were not. the park said they didnt allow 'headgear' of any kind on certain rides because they can become projectiles. fair enough. hats, glasses, etc. these things could cause personal injury to someone if they got enough speed and hit someone in a sensitive location. a head scarf is incapable of damaging anyone no matter how fast its going or how direct the hit. certainly they should have been allowed to wear them.
that being said, islam is a poor choice of religion.