Yes, why are they putting all the HD on one sat?
Essentially 61.5 has a sick satellite. They moved another one over there to cover, but it does not cover the north east as well as needed.
It is easier for them to use the available space on 72.7 which has a new satellite that was just launched instead of worrying about more failures at 61.5 and upset customers in the NE that get patchy signal by the temporary satellite.
It appears their current strategy is to move all the national programing, both SD and HD to 72.7. It also looks like locals will be on 77 until it gets its new satellite which will have a lot more local capacity via spot beam. 77 will probably have a mix of CONUS (plus Mexico coverage) and spot beams. It is unknow what the CONUS coverage will be used for (some speculation of being Spanish programing for the US).
61.5 is slated to get 2 new satellites, one for CONUS and one for spots. Once they get those in place no one really knows what they will use the CONUS space for at that time. The spot beam satellite of course will be used for locals.