English teacher here. 1. Show the teacher a draft and ask if this format (poem in the middle) is acceptable, or if he wants a totally prose essay. If he says yes, then 2. If you wrote this poem beforehand, 'fess up to that and ask the teacher if it's OK to include it in this essay, since it answers the prompt so well, but you didn't write it for this prompt. Also tell him if you turned it in to any class for any assignment.
I also agree with your other advisors to 1) Not be arrogant, 2) Don't disdain any other genre of literature (or is 'disdain' just a poor choice of words?). 3) As Obi advised, try to find out what your professor wants rather than what he says he wants. I am sometimes pleasantly surprised by a student who thinks outside the box, but last semester I had a student who insisted on writing essays in a creative, poetic, telegraphic style that vividly conveyed images but didn't use complete sentences. I helped him to see the difference between creative writing and expository writing and helped him get into a creative writing class before he had the prereqs, just to keep him motivated. I hope this helps.