I'm fairly sure Apple doesn't terminate the developer account simply for failing an app review. I think this is a specific executive decision based on the fact that Epic is unlikely to rectify the issue, which could be seen as retaliation.
This was explicitly not a case of a failed app review. Epic rolled out their direct-purchase option with a server-side update (specifically to side-step Apple's rules), which falls afoul of Apple's developer agreement in two ways -- it would be classified as misrepresentation of the app as well as an attempt to mislead Apple during its app review. Apple reserves the right to block updates (which they haven't done _yet_, as Epic hasn't submitted any updates), delist the app (which they have done), remove the developer's account to block updates, and to blacklist the app entirely (eg: the app will stop working even if users already have it downloaded).
Section 11.2 Termination, subsection (f):
> (f) if You engage, or encourage others to engage, in any misleading, fraudulent, improper, unlawful or dishonest act relating to this Agreement, including, but not limited to, misrepresenting the nature of Your submitted Application (e.g., hiding or trying to hide functionality from Apple’s review, falsifying consumer reviews for Your Application, engaging in payment fraud, etc.).
In this case Epic hid functionality from Apple's review, with the intent to bypass further rules in the Developer Program License Agreement.
Apple is allowed to terminate the agreement at that time.
Epic has made it particularly clear that they do not intend to cure the breach, and Apple has made it clear that in that case they are not welcome to have an Apple Developer Program account and the permissions that grants a user.