The second irony is Murdoch can once thank rival Comcast for making him money if he ends up with the networks.
When Comcast and Disney were jockeying to buy Fox assets earlier this year, one thing was never in doubt -- Murdoch wanted to sell to Disney. Several times, Murdoch aligned himself with Disney's bids against Comcast.
Yet, the competitive Comcast bids let Murdoch net $19 billion more for his bundle of assets.
Now, Comcast's participation could help him get the sports networks at a bargain.
Disney originally agreed to buy the Fox assets for $52 billion. Comcast's rival bids for Fox pushed the price up to $71.3 billion. In that process, it pushed valuation of the RSNs higher, as it did for all of the assets (including 39 percent of British TV provider Sky, which Comcast later agreed to buy).
Disney almost certainly won't find a buyer that will pay that inflated valuation for just the networks. New Fox's most likely competitor (barring a competitive bid from a company like John Malone's Liberty Media) is a private equity firm -- and there's little chance a leveraged buyout firm could win a bidding war for the RSNs and satisfy its limited partners that it would make a future return on the assets.
(Disney, by the way, will end up getting $15 billion back for selling its 39 percent stake in Sky and possibly about $20 billion for the RSNs, making that $71.3 billion Fox deal look more like $36 billion.)
It's possible Google, Amazon or another technology company would eventually be interested in the networks for the sports rights. But that seems unlikely. The regional sports networks are tied to a legacy cable system that tech companies typically view as anathema. If Amazon or Google wants regional sports rights, they can just wait until current contracts expire and bid on them then.
The final irony is Fox's decision to sell the RSNs to Disney may have actually convinced Murdoch that it was better off keeping them. In the months following Fox's decision to sell, New Fox has clarified its focus, centering itself around news and sports. Netflix publicly praised the company for that decision last week.
It's possible Fox has come to the conclusion owning the RSNs makes more sense than selling them, even if it didn't think so 10 months ago.
Disclosure: Comcast is the owner of NBCUniversal, parent company of CNBC and CNBC.com.