Being that I'm not sure about the whole story I couldn't say. Was the boy harassed (mentally, physically, sexually) by this girl before? Had she touched him before? Is this girl a problem? Had she been warned previously, but because he's a boy no one took him seriously? Just because he was asked doesn't mean he would want to look like a wuss and complain about a girl touching him.
How would I feel if the genders were different? Would I be more tolerant of this mother doing this if it was a girl complaining about a boy?
On one hand it seems a bit much, but I just don't know enough to make an informed opinion on it.