mind boggles

So the "nursing" issue was never talked about in our classroom, and the parents weren't really notified in any conclusive way- keep this in mind as i tell the next story....

Yesterday a boy in our class bit me and another child- no skin was broken but there was definite biting with intent to harm going on. This boy is one of the younger kids in the class, super physically active and has some speech issues wherein he gets very frustrated when his needs can not be articulated in an understandable way... He bit another boy because they were climbing on the slide together and the biter got pushed and shoved by the bitee.. and the end of the day the biter's communication breaks down even more due to tiredness and over excitement over the playground.
I spent an hour on the phone to his parents at the insistence of my head teacher- remember her the one who insisted i need not say anything about a boy's mouth being on a girl's nipple in a bout of very realistic pretend nursing? So i have to ask again where is the line with her? what is she considering appropriate and not appropriate? Why is a mouth on one body part different than on another?
my mind boggles