So I called in and it seemed like a very regular request, no hesitation on how to handle it. They can produce a reservation confirmation too and it can be pulled on MMB. Itinerary clearly states "RESERVATION WAITLISTED, BUSINESS (U)"
Interesting observation was that they don't charge taxes until waitlist clears, and I guess this means they must process waitlisted awards a bit earlier than the T-37 hours used for upgrades. (I think she told me the cut-off-time, but I didn't hear it well enough)