I just phoned the school wanting an update to the matter and i spoke to the Librarian, who answered the phone as she was helping out the office people. So i had to briefly explain the situation to her and she said...

"So you have a problem with your son learning this?"

WTF.

I said "Yes i do"

I couldn't believe it. I sent an email with the comment i got from the librarian, wanting somebody to call me back urgently regarding this matter.
Far out! I'm sure that instilled you with a whole lot of faith in getting a resolution, not. There are so many other ways to explain racism/discrimination in an age appropriate way. Just like you don't explain violence to a group of 7 year olds by talking about rape.