That article is not a lie. It says Red Hat is no longer publishes the sources the way Alma consumed them.
The phrase "gating all its own contributions behind a subscription paywall" is a very different statement.
All RH contributions are public.
Even those RHEL patches, which go to minor-stream branches first and not land in the CentOS Stream directly, _must_ be brought into CentOS Stream before the next minor release of RHEL by the development policy.