The report doesn't mention when the PF actually retracted the speed brakes. Were they left extended until auto retract at Alpha Floor? Am aware of this scenario occurring previously with similar results.
Tough crowd this pprune thing, can't help but wonder how well some of the commentors would have handled this situation in the early days of their high performance jet careers.... FL380, a rather reduced flight envelope, alone on the flight deck with a PFD full of carnage. Not an easy place to be...
Leave the automatics in, let it overspeed, there will be considerably less paperwork.