Many people seem to be in agreement that there's nothing wrong with long hair on a boy. I also happen to argee. But that's not the point here.
The point of this story is that the rule is already in place and this mother is choosing to fight it. Fighting to change a rule that you don't agree with is fine. However, it's not fine to do it at the expense of a little boy's education and, in the process, parade him in front of cameras. He's being suspended and made to sit in a room away from his class. This is a choice his mother is making by refusing to cut his hair and, thus, causing him to break the rule.
If she doesn't like the rule, she could start a petition and take it to a school board meeting. She could do some research and poll similar schools on their policy about long hair on boys. Then she would have data to back up her claim that the rule should be abolished. There are ways to go about inciting a rule change. Causing your little boy to suffer, to me , is not acceptable.