One thing I wondering about. Why skylab? You have SeaDragon! You can put up the iss in one go! Multiple bigger ones infact, one for the airforce one for nasa/esa even. Why work to keep that one up when ragone probably wonts his freedom station at this point.
Some possible reasons:
Sea Dragons are relatively rare and/or tasked to lunar operations and nothing but. Therefore you’re left with what an old Saturn can put up.
We know it went up later than OTL, possibly much later. Possibly not until the shuttle fleet made it feasible to crew it and the still-expanding Jamestown at the same time, so late 70s? So it might still just be a matter of operational life.
Also it could be that Russia (again, later than OTL) starts putting Salyut together and Reagan is like, “heck no, what can we do?” And NASA is like, “literally we can do this tomorrow,” and show him Skylab. “Perfect.” And then it’s this red-headed step child we’ve launched on a whim that needs to be maintained as part of the general pissing contest that is current foreign policy, but that doesn’t mean the administration ready to piss MORE than they already are just yet.
And maybe another reason is politics. Maybe we want bigger commitments from allies, or they want a bigger say, or both. So we’re waiting on independent launch systems from the ESA or Japan, or we’re still wrangling over crew and composition.
One would hope that by the early 80s, the second-gen facility is nearing the deployment phase. Because I agree, Skylab is literally the least you can do.