After @vatsal jumped the gun and my own premature evolution I think I've been able to wrangle my ducks in order with the binary framework project and release it for general use. It took quite a while to get the holy trinity working (building, source editor and previews) and then there are all the platforms you need to build and package – but we should be there now. All the information you need about how to use it should be in the README
I consider the concept well and truly proven now but it won't become a solution until people use it. If your boss is worried about downloading random binary distributions they should remember macros execute in a very restrictive sandbox. Perhaps Apple will come up with something similar in the future or distribute frozen versions of swift-syntax with their toolchains but the approach of dragging the repo onto your project to override all references to the swift-syntax package in macro packages has its own merits which may avoid a good deal of versioning conflicts in the future.