But medical providers aren't commissioned as advisors, they're commissioned to actually deliver services, right?

I'm not aware of any contemporary cases where someone direct commissioned but agreed to a lower "dollar-a-year" payscale. I think our prior assumption should be that these four people are on O5 until we hear for sure.

They're O5s. But in the reserves, so they won't be getting paid much unless they're activated.

Sure! Also: I am saving a lot of space for the underlying arrangement here being super weird and norm-breaking, for obvious reasons.