While I agree that this is the best path forward, I just want to reiterate that it is imperative that we immediately follow this up with a DO to BS. We really do not need a point of weakness in our alliance with the upcoming Maharatha Sketch nonsense.
I think that, if we explain things, the Black Emperor will be understanding. At the very least, we'll have been incredibly consistent with our diplomacy here. We tried to stop the fighting, admitted the WBS had valid grievances but honored our alliance with the emperor and sided with EBS. When war became inevitable, we minimized the bad blood while working on a real solution, and when peace was proposed, we accepted it and immediately set down a path for healing the rift. The Black Emperor may not like things, but it's not like we're pulling the rug out from under him here.
Plus he gets free rails. Everyone likes rails. Because we told them they do.