Batista was pissed that he lost to Shawn Michaels. Evolution said they wanted to go 3-0 at Armageddon. Flair suggested entering the tag match and getting the tag belts, which by my vantage point, is a pretty darned good consolation prize. Evolution uses their connections with Bischoff to get the job done.
Bingo. Evolution comes out smelling like roses, even if one of them did lose.
And for all you people who'll have a coronary if HHH keeps the belt, I honestly doubt they'll keep it on him for much longer. He'll lose it at the Rumble at the latest, methinks.