If MPC renewal is the primary objective (vs miles to burn etc..in a 'care much more for' manner), it might be worthwhile to:
A) create the MPC case for the retroactive claim
B) start a separate thread/case with them on DM renewal, pointing out that while you are working on #A , you are disadvantaged till #A gets sorted

And potentially, forget about #A (given the hassle involved) after #B is sorted...

I had a potential issue with my status renewal a bit back- UL /QR flights were taking a long time to post on retroactive claims, and I'd screwed up in my attempt to 'optimize' things..wrote in and they replied along the lines that I should let them know if there are bookings on which I'd not be getting my DM/EMERALD benefits because of the delay in resolving my renewal..

My money on them just renewing your DM 'given your continued loyalty'..