There is no legal issue or requirement that Dish use spotbeams. Spotbeams is a matter of efficiency. Now, when Dish used to provide Distant Nets, they had to lose some efficiency by putting those stations on ConUS. However, after Dish lost the legal right to provide Distant Nets, there was no longer any point to wasting the bandwidth on ConUS for stations that could now only be viewed in their respective DMA. Since those Distant Nets no longer had a need to be on ConUS, Dish put them on spotbeams to realize greater efficiency, but no legal requirement to do so (as the access of channels is controlled by the software on the STB regarding access)
This is a very similar situation with the RSN's. Ideally, they should all be on spotbeams to realize maximum efficiency, but Dish has a package to provide all RSN's to all subs throught the country, so now the RSN's are eating up the precious bandwidth on the ConUS. But Dish can put any channel on any type of transponder it wants, the FCC doesn't care because the issue is access, meaning what the STB software will allow you to see.
In fact, for years, all the LIL's were ConUS because that was the technology then, but you may remember, your STB could only see and access the locals in your DMA (or Distant Nets) even though several other LIL's were streaming down to your dish and into the STB, but the box never allowed you to see or access them. In fact there are still some LIL's on ConUS, today.