I agree, if it's good enough for the basketball team to attend en masse I see no problem with an 18 year old woman working there.
If it isn't an NCAA violation (Really, does anyone get a cheerleading scholarship that prevents them from working???) I don't see the school having a legal or moral ground to stand on.
The only thing I could see the school dismissing her from her squad would be if she wore parts of her cheerleading uniform while performing her professional duties. If she didn't I side with this woman.
Sometimes we take the midget (16 & up) hockey team to Hooter's after a game but that's only when they win.