The developer (john doe) honours the EULA up to the point where the sources are on his computer and cancels hist account (or has RedHat do that). From there, it's just GPL code that can be re-destributed freely (save for RedHat trademarks and licensed assets).
The company (rocky, alma, springdale, oracle) is in it's full right to accept any changes and merge them into their GPL code base.
Sure the ethics are questionable, but I suppose the IBM lawyers would have a hard time prohibiting this in the EULA while simultaneously honouring GPL and welcoming contributions from anonymous developers.
But I suppose I'm just too dumb to see that my cunning plan isn't very cunning at all. :-)