Agree, I was thinking about that as well, but this would require to track the detection workflow and store some reasonable messages about what it's been doing and show them when this conflict arises.
Beside this the client part 'AskUser' which shows the dialog with target radio buttons is a separate workflow from the 'MakeProposal' part, which means I would need to store those messages outside the client (in SystemdTarget module I think) . 
I try to add that into the next commit.