I think the cave-ins are a recent issue, just like the very start with SGS itself being stuck easily at its own doorstep (I'm actually betting on the whole Cube business being the cause for that too either directly or indirectly via Faceless tunneling towards CC), otherwise how does Fort Apogee(?) stay supplied, who in turn also supplies SRO (logically anyway I figure), who also supplies their interests such as Rail Crossing and the Junkyard Embassy? They don't just cart in personnel, perhaps even more than that they are seen heavily moving all sorts of gear, which has to come in from their North territories via freight through the tunnel you pointed out. Blockade can't be there the whole game.... one hopes. Yeah, had figured pipe dream, but would have been nice, even if just the first stop up the tracks from CC through the blockade.
And had not meant the entirety of the North, just something to give a feel of Protectorate and the Drone fight in their own territory, instead of just having to see the expansionist side of the Protectorate.
Given the border outposts location, Omega must be a bit past the Hathor location I think, far beyond what we got right now. All other locations remotely in that direction are quite derelict being why, and the Omega situation occurred relatively 'recently' given Gorsky is still alive and a participant for their facilities to have fallen quite to that level of disrepair. The GMS thing could easily be argued for it except for it being way too close to SGS and kinda flouts the border outpost fluff. WIsh could do more there, such a waste of a functioning base... damnit, Gorsky, whyyousoblind.
I'm patiently waiting for more to do with the Junkyard/Wyatt deal and that story, too.