perl spam when running tuxmake without a runtime

When using tuxmake without a runtime (for example, testing a locally compiled version of clang) on a non-Debian based distro (Arch Linux in my case), I sometimes see a ton of spam around not being able to set a locale:

$ tuxmake -t clang LLVM=1 LLVM_IAS=1
...
perl: warning: Falling back to the standard locale ("C").
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LC_COLLATE = "C",
        LC_NUMERIC = "C",
        LANG = "C.UTF-8"
    are supported and installed on your system.
...

This seems to be forced at https://gitlab.com/Linaro/tuxmake/-/blob/master/tuxmake/build.py#L342.

Is there any reasons that LANG=C cannot be used? Not all distributions have C.UTF-8: https://unix.stackexchange.com/questions/597962/how-widespread-is-the-c-utf-8-locale

To easily reproduce in docker or podman (with an existing Linux kernel checkout, adjust the volume paths accordingly):

$ podman run \
--rm \
-ti \
-v "${HOME}"/cbl/src/linux:/linux \
-v "${HOME}"/src/tuxmake:/tuxmake \
-w /linux \
docker.io/archlinux
# pacman -Syyu --noconfirm
...

# pacman -S --noconfirm base-devel bc bison flex libelf openssl python
...

# /tuxmake/run
...
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LC_COLLATE = "C",
        LC_NUMERIC = "C",
        LANG = "C.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
...