Personally, it would never occur to me to request a specific number, and if I were in charge I would probably find it annoying to accommodate all sorts of special requests. So to me, it makes more sense to issue numbers in order. Plus, it make seniority self evident. Lower numbers were earlier joiners, and vice versa. But since the policy has already been in place, things get a little more sticky.
I'd probably still stop it. The special requests that have already come in, great. Grant them as best you can. Those early people got a benefit for being early people. Us later people, we get what we get. Hahaha!
Welp, I would handle the special requests that have been requested already, then move on to whatever numbers are available. Another option i just thought of would be if you want a specific number then become a supporter of "OB". OB supporters get first dibs?
I think it would be alright to request your own ID number as long as it isn't taken yet. On the other hand it would be a little bit more annoying for Michael to order all the custom number configurations.