RHEL Clones: Take finished source code, rebuild, test, release.
RHEL: Work upstream to develop features / submit features upstream before inclusion in RHEL, maintain specific versions of upstream, test hundreds of upstreams together to make sure they can be shipped together as an operating system, develop "glue" software like Anaconda to install + manage the whole thing, take source, build, test, release, accept bugs, start over again for next minor release or major release as needed.
And, of course, this elides all the certification work that makes RHEL an attractive enough project to rebuild in the first place because people want very specifically a RHEL compatible distribution to run an application or applications on top of.
What people get pissed at Red Hat about isn't that they don't get to access the source. They're pissed they don't get the convenience. Largely speaking, the people who get pissed aren't concerned about Free Software, either - they just want easy to run binaries. As I understand it "get binaries for free" is not mandated by the four freedoms. The source code is still out there for people to study, change, use, and redistribute. That seems entirely compatible with the free software ethos - but incompatible with the freeloader ethos.