Vaporware? Or just a paper tiger?
It's too bad they never built this sort of capacity into the ISS. That would have given the design longevity and validity beyond the absolute face-saving minimum. It would also have evicted the microgravity experimenters from ISS, so that they could have had a more meaningful platform free from the disruptive presence of astronauts and their vehicles.
Something common to this plan and the early Freedom "orbital harbors" is the use of actual physical hangars for thermal and micrometeoroid protection. An argument in favor of the ILM space mushroom?