Urgh that vagueposting regarding the "ban" ... I looked around quickly and I'm guessing he is referring to something adjacent to:

https://lists.gnu.org/archive/html/guile-devel/2011-12/msg00107.html

Because that seems to have been a bit contentious. But then https://lists.gnu.org/archive/html/guile-devel/2011-12/msg00205.html seems rather conciliatory. And https://www.gnu.org/software/guile/manual/html_node/Local-Evaluation.html did in fact end up in #

But then https://packages.debian.org/buster/lilypond looks like it vendors guile-1.8, so I guess it wasn't enough? There's a debian bug also that I haven't read yet ("please migrate to guile-2.0").

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=746005