He got it from the same place we all did; from the Terms of Service in the game, or even on the box in the small print, but I'm not sure on the last bit. They can , and I quote; "multiplayer features can be changed or removed at any time without notice"

The whole point is that they don't need to do anything at all with MP, just look at CoD4 and W@W; those are no longer supported, which they can quite easily do to this game or any other CoD.

It supports multiplayer. Online multiplayer is only supported for as long as the Developers and publisher chooses to support it. Technically all the past CoD's have lost their support from the Devs only a matter of time before they decide it's not profitable to keep running their online service all together.

For example; Army of Two no longer supports online, though it once had the option. As with BF2:Modern Combat, and a bunch of other games. It's not uncommon.

If the past is any evidence once Microsoft makes a new system shortly afterward they will discontinue all functionality of the current Xbox's Xbox Live.