This is the crux of the issue. Pretty much every opinion in the ruling has one opinion or another about how the case would've gone differently if the "market" defined by the district was broader. In this case, the market was "mobile gaming transactions".

  The district court analyzed anticompetitive effects
  in terms of increases in the cost of mobile gaming
  transactions—the court’s relevant market. But the court
  could have found greater increases in costs if its analysis
  concerned Epic’s markets, and this would change a properly
  conducted balancing analysis. In essence, any balancing
  done out of the context of a relevant market necessarily
  involves putting a thumb on the balancing scale.