illegal equipment/uniform

Question
I saw a girl pitching in a MN high school game with a knee pad that is optic yellow.  It even had simulated seams drawn on it.  I stood behind home plate and it was a tremendous distraction for hitters.  Umpire in chief said there was no rule that prevented this.  Really?

Answer
It sounds like a mizuno sliding pad that was reversed, rolled off the knee.  I know exactly what you are talking about if it was.

This could easily be interpreted as violations of rules 2-9 and 2-10 regarding the uniform.  I wouldn't allow it on any player.