As the CentOS Stream community grows and the enterprise software world tackles new dynamics, we want to sharpen our focus on CentOS Stream as the backbone of enterprise Linux innovation. We are continuing our investment in and increasing our commitment to CentOS Stream. CentOS Stream will now be the sole repository for public RHEL-related source code releases.
It would count as an unauthorized use of the subscription, so Red Hat wouldn’t keep doing business with them, and wouldn’t receive the source code.
That sounds like a giant GPL violation if sources are provided under the condition that you don’t use them.