Fly...I'm a teacher too, though of middle school art students. I am lax and laid back with them, but am realizing there has to be a cut-off point in which the teacher says "NO." You responded correctly. Compassion aside, this EMT, big fella has not fulfilled the class assignments, and is "playing" you for all it's worth.
You responded correctly and professionally.
I'm in grad school right now, and if I did such a thing, I'd get an F!
Patty