At our old school, we had a similar experience. They were quick to offer accommodations without a 504. I just kept steering it back to eligibility. Since he meets the criteria, he's eligible. Full stop. He was the first kiddo to get a 504 for food allergies in the district- and it was only three years ago.
Then, after that, they kept trying to say "oh, we don't need to put that in the 504- it's just our regular policy." The response to that is, "Great, then since it's policy, it won't be a problem to add it to the 504."
Given the principal's wishy washy-ness, I'd be extra sure to get the 504. He qualifies. There's no down side to having one for you or him. The only down side for the school (since they're offering you all of the accommodations anyway) is the accountability... which is a huge thing for you guys to have in place.
Good luck!