I often think of Debian as a bit moldy from some changes over the years with legacy support (kludges?) in place, where it seemed more like an outdated Arch Linux at some point once it had switched to systemd.

But if I were CERN, I understand the choice of not getting involved with newer forks that aren't novel distributions you can trust to be around for the long haul. I would choose Debian as well in their place.