Alaska Airlines (AS) Mileage Plan MVP members do not get Elite Upgrades on CO metal, nor do we get that treatment on AS.
FWIW: the flights DO NOT have to be code-shares w/ CO/NW flight numbers for the Elite upgrades on each other's aircraft.
I would be willing to bet that there were not (10) CO/NW Plats, more like any color Elite that got to the airport before you did

the flaw in EUA and the Elite Upgrade process...