Again, he said that they would be "senior styled" not that they would specifically be senior photos to be used in a yearbook. The photos could have just been a portrait style. Furthermore, I was probably excited about getting my first potential client, that I didn't add all of the details up until later. And after realising the true kind of photos this person wanted, and then the model's age, that I was put off by it. Which resulted in me saying no, to the offer. Also You can still be an adult in high school, I was 18, making me an adult, during my senior year.
I'll just have to be more selective when it comes to accepting shoots! But I really do appreciate everyone's input here.