Yes they must abide by the terms of the licenses of the software they redistribute. But they could start licensing the parts they write more restrictively, like

Yes they must abide by the terms of the licenses of the software they redistribute. But they could start licensing the parts they write more restrictively, like RPM spec files. I don't think this will happen given how much back and forth there is between RHEL and Fedora, but IBM is in charge now.