MS shuts down Halogen mod ... why now?

The story so far: for three years, a group of eight modders came together to create Halogen, a C&C: Generals mod based on Halo. The mod gained popularity, and just recently Microsoft and Bungie decided to shut the mod down -- a decision that is very much in their right, as explained by this forum post. However, as the mod would neither be detrimental to the Halo image (it was very well made, as the images show) nor profitable for the team, why is Microsoft serving a cease-and-desist now?

1UP's Luke Smith puts on his tinfoil hat and speculates that Bungie might be returning to the real-time strategy genre. If memory recalls, Bungie's first post-Marathon title was the 3D strategy title Myth: The Fallen Lords. And Halo was originally going to be a strategy game, as revealed on the Halo 2 Limited Edition DVD. Smith connects a few key Bungie members to Texas-based Ensemble Studios (Age of Empires) and concludes that they might be working together.

It's all massive speculation, although more Halo titles seem very likely. As an RTS, though? We'll hold our breath, hoping Bungie can break us from our real-time cynicism; in the meantime, mourn the passing of Halogen with a trailer for the mod, embedded after the break.