They run a cloud VM with a paid RHEL AMI and use it to pull the sources. :-).
This is a big part of the reason there's so much uncertainty in the RHEL community right now...
IBM is big enough to make an example out of a few unlucky individuals, and compel everyone else to play their way.
If they forbid this they lose the right to use Linux.
Not anyone can just bring a suit to compel compliance - and IBM has much deeper pockets anyway. So even if the suit was righteous, it would be dead and buried long before it saw a court room.
Additionally, the Kernel is only a tiny portion of the RHEL distribution. There's plenty of proprietary RH/IBM code in RHEL, and a ton of non-GPL'ed software too.
Lastly, a RHEL license contract might be updated to explicitly state you are forbidden from distributing RH sources... which would kill Rocky's "work-around" while still being GPL compatible.
GPL isn't some magic bullet like some people believe...
Unless it's Oracle that sues them.
Even the people who don't think what they already did was a GPL violation would consider that to be one.