Unfortunately that's triggered by gnome-session when requiring a logout, and we can't do so much about this mostly because the gnome-session is not giving us a list of inhibitors before that an action is requested.
So, to get this we'd need to fix the interactions between gnome-session and its clients and then to change indicator-session to directly call the unity action to perform (and not gnome Session).
At this point I think it's too much work for the noise it causes.
Unfortunately that's triggered by gnome-session when requiring a logout, and we can't do so much about this mostly because the gnome-session is not giving us a list of inhibitors before that an action is requested.
So, to get this we'd need to fix the interactions between gnome-session and its clients and then to change indicator-session to directly call the unity action to perform (and not gnome Session).
At this point I think it's too much work for the noise it causes.