The original question was about whether users MUST make config "Free Software"
Guile says:
"Scheme level code written to be run by Guile (but not derived from Guile itself) is not restricted in any way, and may be published on any terms. We encourage authors to publish on Free terms."
https://www.gnu.org/software/guile/manual/html_node/Guile-License.html
Seems clear to me. There is no **requirement** on users to make their #guix config "Free Software" - users can choose what they want - freedom of choice.