You probably could get away with it, but that's really not the point.

You sign the waiver and agree to abide by the race rules, not abide by the rules except for the rules that you don't like.

It's not just the concern that people with headphones don't listen to race instructions and may not hear traffic or announcements on the course, runners with headphones also can and do bother other runners in the race, perhaps without even realizing that they are doing so. That's why headphones are banned in so many large races.

Leave the headphones at home. You don't need the distraction - especially if you are not used to running in the middle of a huge crowd, the other runners don't deserve distracted runners on the course, and you'll be able to enjoy more of the race atmosphere without them, anyway. Enjoy the whole race; take in the whole race atmosphere with all your senses; and leave the headphones for your solo training runs!