Why is Ubuntu/Debian sticking to polkit 0.105?


I am working at a university, where we also deploy Ubuntu 18.04. One of our requirements is to restrict access to certain actions on certain systems, depending on use case. To be more concrete, we need to deactivate the shutdown, reboot, hibernate etc. functions for certain users.

Of course there is no problem in restricting those on the command line but it is a bit more difficult for the desktop shell. With polkit 0.105 we are able to restrict access to such functionality however, it seems like we can only block it for certain users or groups of users without the possibility of whitelisting others. This is in fact something the polkit author himself criticized in the past, which led to a rewrite of polkit as of 0.106. This version introduced a breaking change in how polkit rules are written of course. This leads me to my question.

Why is Ubuntu or rather Debian sticking to polkit 0.105 instead of implementing the newer polkit versions? Is it because of the breaking changes introduced which lead to rewriting the current rules?

They are evaluating if they can update it: Use of Javascript rules in polkit