Given that it's a few minutes from the terminus this sounds like a good enough reason to avoid moving the resources to Central!
At the other end of the route driver changeover used to occur at Ferrymuir, which wasn't quite so daft. However changes were sensibly moved to Borrowman Square a few years back.
It must be easier having driver changeovers in Queensferry for that regard as I assume they do the same for the 71, unless the driver changeover is somewhere else on route due to the split between services.
While I get the arguement for the 43,70/71 going to Lothian, the fact is, they are established Lothian Country routes and they work for what they are, and having a strong West Edinburgh network should be a priority, plus eliminating these routes would eliminate the City west Zone which in turn would eliminate cheaper tickets to/from West Lothian for those in that part of the city.
As long as Lothian keep up the standards, it shouldn't matter, however it does beg the question if the services are well used.
I hear the 71 does well, but what about the new X19?