In this case I assume their "fear" is that unprivileged users can exhaust resources (inodes, filesystem space) in an important tmpfs breaking the system. The proper solution for backward compatibility would probably be something like make /run/lock its own mountpoint, but they fixed it in their system (Fedora) so now it's no longer their problem. Just be thankful their software is portable to such strange niche operating systems like Debian. /s