FCC wanted Dish to deploy its spectrum, Dish was hesitant to enter a 4 player market making it a 5 player market. This merger solves couple of problems. It solves Sprint's capex problems, T-Mobile's spectrum problem and Dish's (and FCC's) spectrum deployment problem. Win, win, win!
One thing that we have forgotten is this may not be a pure win lose court case. If you read the FCC order you will note it is missing the appendices that would cover county by county spectrum screens yet they are mentioned in the table of contents. The ruling specifically tells the Wireless Telecommunications Bureau how to handle the Dish licenses but not the Sprint licenses which would be the next step. Likewise the DOJ never went to the next step of buying national advertisements to start the Tunney Act process. Basically the state AGs court case seems to have frozen or taken over these aspects. In smaller mergers these details are often handled by an administrative law judge.