Earlier quoted context omitted.
Epic Games can argue that a cheaper price results in more demand, ie more profits for them even if the unit price is the same. But I don’t think they need to argue that. The cornerstone of US antitrust law is cheaper prices for consumers. This example demonstrates that.
But the point of business is making money. Apple has no monopoly in smartphone market. There are many choices. And if the court will force them to lower prices - will it start forcing price policy on other non-monopoly companies?
Google can have the argument that you can install different stores in their OS (or even apps directly), and so you’re not locked into the Apps provided by their store. Apple can not make the same argument.