Heck, we do not even do unit propagation of negative units yet; i.e. if we mark a package as not being installed we do not mark its reverse dependencies as not being installed.
This requires us to add "negative" work items. So like "install one of these" it is "mark all of these as broken".
i.e. we install a, a Conflicts b. We insert a work item to mark b as not installable.
We get to "b is not installable". We mark it as such and then queue its reverse dependencies as not installable.