Hint - merits does not equal required. You said this earlier:
the officer was focused on protecting the public, that's his job...[th]his officer was protecting the rights of the parents, again... thats his job.
So you said JUST THAT - that police action was acceptable here, even part of his job. Now, I would like you to find ONE police jurisdiction that has listed as an official duty for their officers that they ensure that offensive materials are not hung in classrooms. I'll be glad to give you all the time you need.
If there was no arrest... you got no beef.