The source code IS publicly available in CentOS Stream gitlab repos. The thing that isn’t public anymore is the pre-packaged SRPM snapshots of that code. This effectively means that if clone makers want to keep cloning RHEL, they have to pull from CentOS Stream and do some Engineering work instead of throw a script at a pile of SRPMS to rebuild them. This whole thing has been weirdly blown out of proportion in my opinion.
Disclaimer: I work for Red Hat so feel free the grain of salt my statements and flame me if you feel so inclined. I don’t mind people being upset about the change, I just want people to be mad at the right thing if they are going to be mad.
Red Hat also maintains the software they ship to customers for 10-15 years, LONNNG after upstreams have abandoned them.