BOAC-
I believe the alpha-floor term came around for 2 reasons - It is derrived from Bus speak (getting into that now) and the flashing 'A' symbol that appears on the MCP when active. Do you remember the good old girl (-200ADV) which actually had an alpha symbol arrive in the speed window when active! You put the clues things together and end up with Boeing pilots stealing an Airbus term. However the MSR on the 737 is completely different to Alpha-Prot/Floor on the Airbus!
I don't believe the MSR would have helped in AMS - Having giggled at several colleagues when MSR has activated at 60' - Only to have the MSR revert to retard passing 27'. Which leads me to think that the retard has priority over MSR hence it wouldn't have helped in AMS. That is if the NG behaves like a classic in that way....
Cheers, Cough