Nah... it's because you ate it... damn you purple ball. [spoiler]And now your evolved form lurking in the tower, siphoning off naive guardian's light as they bounce you around...[/spoiler]

They just simply said there wasn't a raid with HoW. They said the next raid would ship out later. Which sounds like it'll be tagged with the comet, but that's speculation. As to why it isn't a part of HoW. That is also up to speculation. They could be polishing it, could just be -blam!-ing the players over, or they could just be trying something new. I guess we'll see