Of course, the reason why Disney couldn’t buy them in the first place is because acquiring the RSNs as part of the 20CF purchase would have given Disney too much market share in sports broadcasting… what with ESPN being the largest cable sports network, and its namesake subsidiary owning eight sister channels in the U.S. alone, a pay-per-view unit, two streaming platforms (ESPN3, then within the now-defunct WatchESPN app, and the then-fledgling ESPN+), two radio networks (plus a Sirius/XM channel), and holding control of ABC’s sports division. So, the only options for 21st Century Fox were to pull the Fox Sports RSNs off the market and retain ownership of them or sell them to a third party (as they ultimately did).
Quite frankly, as much as Murdoch selling 20th Century Fox, and the FX and National Geographic networks didn’t make much sense (especially when that library would have been useful to them from a streaming standpoint as Disney was able to do with those properties), selling the Fox Sports regional networks didn’t make much sense either, given that the Murdochs’ deep pockets allowed 21CF to clearly be better able to support the RSNs than Diamond Sports was. At least Fox Corporation wouldn’t be saddled with enough debt managing them to drag it into bankruptcy compared to what Sinclair is now dealing with, nor would they make the same mistakes with carriage agreements that Diamond/Sinclair made that contributed to its financial troubles.