They don't use Steam in their games anymore than they use Wal-Mart in their games
Uhm, yes they are. Call of Duty: Black Ops (released a few days ago) is sold in stores as a DVD that installs steam and then installs the game as if purchased online via steam. This has been true for many titles before this one.
Basically, since users now has steam installed (and a steam account created) the barrier for further purchases over Steam has been lowered significantly.
I'm not saying it's a bad thing, but I guess that's what they mean.