I'll give some slight insight on maybe why it's changed. I was the last one picked up at AZ under a different commander, this past board and the one coming up are under a new commander. I guess he's changing the requirements . It used to be AZ Guard only(Army or Air), unless it got pushed back due to no qualified applicants, then they'd open it up to military only. Looks like he's opening it up to all.
Technically you're under the AZ Guard until you find that unit. So you're sponsored by them, until you PCS fully after 16 B-course. I think Klameth/Portland does something similar, but I could be wrong.