Well, the website refers to "licensed" riders, so they're licensed by some sanctioning body (probably USA Cycling). Interesting that they reference the "sleeves" rule, which I think is one of the bizarrest rules in the book. It means you can't wear sleeveless jerseys. Lots of guesses why this might be in the book (some races you might have a number on your sleeves, prevents road rash if you crash, etc).

If you post the URL, I'd be happy to shed some light if I can.

Regarding posted results, the fields may be small, or the promoter may have only posted the top results. Hard to know without seeing the site.

But back to the original question, even without seeing the website, I can almost guarantee that drop bars are required.