I agree that the parents should not confront the coach directly and should go through the process.  In the parents defense they have already had meetings with the principal and ad about the program and had come to an agreement that they would play a limited season because of the low number of players.

I disagree with you that you should allow a bad coach to continue as long as he does not endanger the kids.   If a coach is so bad that a player who loves the game and his school would rather not play or move to a different school says a lot.  If a coach cannot attract even the minimum numbers of players to field a team ensures the lack of opportunity for the players to compete.  

The bottom line is that results matter whether you are a coach, an educator, a businessman or a politician.