Yes, battling dictionaries! Dictionary.com has the definition you offered as the second definition. The first for pornography is:

obscene writings, drawings, photographs, or the like, especially those having little or no artistic merit.

The history of the word hints at its subtext:

1843, "ancient obscene painting, especially in temples of Bacchus," from French pornographie, from Greek pornographos "(one) depicting prostitutes,"

Good writing rests in the words we choose as well as the ones we do not. Choosing pornographic over erotic takes advantage of the suggestion that the subtle difference in their meaning offers. It communicates a value.

I just don't think it has enough to warrant foregoing traditional boundaries in a public school setting.

You may be right. Though, I do get slightly suspicious when people talk like this. We need to be an art critics, historians, moral philosophers, and educators in the span of that sentence. If you have to wear several different hats to arrive at a conclusion, there is a lot more room to make mistakes and turn our own irrational, unexamined beliefs into policy.

Out of curiosity, do you teach this poem? Just trying to get a grasp of why you are so defensive.

Well...

Can you tell me what value there is in sharing this with your students? What will they learn from it?

If you ask a question, someone who answers it is not being defensive. I was trying to help you see what you indicated you did not understand.