According to a post on the official Halo Wars forums, the backlash from Halo fans was the reason for the flip-flop. In the end, 343 decided "that the current plan of action was not in line with how we have always intended to support Halo games and the Halo franchise in general."
Title Update 5--which was set to fix theatre bugs and remove stat-tracking from the RTS--is still coming, but it no longer supports the latter removal. In other words, it's a safe download for Halo Wars fans who love their stats and enjoy checking them on websites. The official forums, on the other hand, will still be moved as planned to the Halo Waypoint message boards. I suppose you can't win them all, right?