I clicked on the link to the message the teacher left. I'm making an educated guess, based on the voice I heard, that this particular teacher is an African-American lady.
It's very likely the parents are racists and are reacting on that basis.
Let's face it, if the kid had pulled out a Playboy or a Penthouse the teacher would have probably done the same thing --- and the parents would probably have had the same racist reaction.
Todd Starnes is at it again, just wanting to agitate "the faithful."