Fungo the HC was wrong. Some will hate him , some will like him and some will hate him one day and love him the next depending on how things go for their kid.
When you coach your in a posistion that is very tough. You can take that posistion and abuse it and use it to control others. Or you can take that posistion and use it to teach others how to control their own fate.
But you have to learn no matter how hard you try , no matter how fair you are , no matter how good your intentions are , there will always be people who hate you. And you have to learn how to accept this and be more concerned with doing what you know is right and doing everything you can to help young people than you are with being liked.
I have a feeling your son is going to be a hel of a coach. I know he is excited about this and I wish him well.