Has Musk, Shotwell or anyone at SpaceX ever said that this was the case? I haven't seen any sign of this at all. And again, if Starbase was just for prototyping workflows, there's no need for two Megabays.
I could've sworn that Musk mentioned that Starbase would be mainly relegated to prototyping after the FAA limited them to 5 launches/year out of there. I think it was in the presentation where they announced the plans to work with T-Mobile? I'll see if I can dig it up later.