Perhaps it is contractual obligations for future HD channels, such as MSNBC, for the reason why Direct is not utilizing the existing free space to add current HD channels? We have seen this occur with channels like ESPN News HD and MLBNet HD, even though there were several other stations they could have added and still could be added that were in HD long before ESPN News and MLBNet.
If they do add MSNBC it will more likely than not be due to contractual agreements. If they do, then you will see several posts questioning why they would add a news station in HD (some may even be political) instead of other channels such as Travel HD or WGN HD.
(Note: I am one that would also prefer to see WGN HD and/or Travel HD before another news station)