The Apple-Epic saga has taken a new turn today as the Fortnite game developer, Epic Games, shared that Apple has terminated its developer account. This is
Maybe a lawyer could tear this apart and find loopholes, but the law should be so simple as to say:
"A company providing mobile computing services and products, being hardware, software, or networking, shall allow under all circumstances and without restriction, the installation and usage of applications from all sources."
But of course, I'm not a Lawyer, so there's probably a loophole to be found in that.