The "Leave..." text was indeed very ambiguous, but I'm not sure "Show logout screen" is better. It fixes the ambiguity problem, but it's a clunky name.
It's a tough one, cause I don't have any better suggestions.
@thisweekinkde@kde@kde re distros caring about PackageKit support: you're hopefully aware that Arch intentionally does not care about PackageKit, in fact the relevant packages were removed from the popular archinstall script some time ago and there's a warning against it in the wiki. The Arch upgrade process requires users to read pacman's output carefully, and as long as PackageKit doesn't allow for that, it's not safe to use.