So what does Peter do when Doc Ock starts tearing up downtown in the middle of class? Call for nap time and hope no-one notices him duck out the window? Freelance photographer is a great job for a super-hero. You work on your own time, with no-one, and accountable to no-one.
Same thing he did when he was a teacher's assistant at ESU teaching classes and stuff.
Heck, it would make for some good stories seeing him deal with that. After all, "great responsibility" doesn't just extend to Spider-Man. Now he'd have a responsibility to his students and seeing they have an education. So what's more important, making sure he does his job or going off to fight Ock when he knows that there are other heroes who can get there faster and deal with him just as well?