NanoRacks hopes to do just that, though not necessarily with a Starship.
https://behindtheblack.com/behind-the-black/points-of-information/nanoracks-outlines-its-private-space-station-plans/

Send up a Starship with a toolkit and some rolls of lining material, leave it on orbit. Punch some holes in the tank bulkheads, deploy liner (anti-meteorite and some radiation protection). Now you have a space station with more internal volume than the ISS. Add solar panels as needed.

This, weighed against current Air Force mobility assets. Lower cost, proven, lower risk, plentiful, easier to train on and train for.

It shift might happen eventually, but I don’t think it will be with Starship.

As for your thought experiment for the ISS. Put a hole through it. Then later patch it, recover an atmosphere and walk in the front door. But this is an extreme hypothetical. And the important question: Why? The ISS is not a worth taking/holding in a shooting war. If we are shooting up there, what’s happening down here?

As for not having anything in space to fight for.
What about other nations space stations? Instead of just punching them full of holes we could take them over intact and use them ourselves.
Or “rescue” the trapped men inside them.

As a thought exercise. How would you take back the ISS if Russia decided they didn’t want any Americans on it anymore?
You would first need a ship capable of at least getting there.

Is there any evidence at this point that USSF is even looking for such a thing?

Their current role is taking care of assets (surveillance, communications, logistical, etc) currently in orbit.
But I have not gotten the impression that deploying manned vessels is being considered.

Even if they were to start “militarizing space” (yeah, I know, but that is a whole other conversation), I think they are looking at ground controlled assets, such as unmanned vehicles, or things that can be ordered and launched quickly (within weeks at this point).

At this point there is no territory to hold in space. Why put a manned vessel in harms way, when they can use ASAT missle or laser systems, or kinetic kill-sats (smash em into each other), or EW (electronic warfare) to jam or fry circuits, or cyber warfare, and simply hack them. All this can be done from the ground. Everything they do is to make sure our assets are available to support actions/campaigns/theaters on the ground. And to inhibit the other guys from doing the same.

Big gamble being taken here….

(PS: Same goes for 1/6th gee too.)

And he does essentially sell launchers. Every time he launches one with no return its basically sold. He just keeps launch control also.

If the government wants them a deal will be made.

The short answer is, “No one.”

To build a self sustaining city on Mars will require 1 million tons + of material and a million people, by Musk’s own estimates. The reality is likely beyond that, unless some of the first actions the colonists take are setting up mining and material refinement on an industrial scale.

Even at 1000 ships (Musk’s current fleet goal) that would take many years to accomplish.

SpaceX will provide transport. They will not provide Starships for sale.

from the snob who wrote his obituary…
“Frank Munsey contributed to the journalism of his day the talent of a meat packer, the morals of a money changer and the manner of an undertaker.”

With a running production line he would only need to reconfigure the interiors for military needs.
Some for personnel transport.
Some for cargo transport.
Some for refueling needs. They will need some fuel to get back to orbit. And of course for in orbit refueling.
Eventually some could be armed and armored for space combat. To an extent.
He could charge a billion dollars a copy and still come in way cheaper than anyone else. How much was the government charged per copy for the last fighter we bought?

He doesn’t need more than 10 for his satellite network. Who is buying all the rest?

Boeing. Lockheed, no one could design test and set up a production line this fast to compete with Musk.
With this one contract he could end up buying out one of those old big guys and liquidate it off keeping all the patents.

Henry Kaiser
“Think Big”
https://youtu.be/jIV4sWbUamU
4:57

Musk is a creature we saw many of in the 19th Century and the first half of the 20th – an industrialist entrepreneur. But they’ve been few and far-between since WW2 and there have been more failures than successes. We’re now seeing something we haven’t seen since Henry J. Kaiser started tooling up to build Liberty ships during WW2 – a flank speed push to begin genuine mass production of something really big.

Alternatively, SpaceX may have developed a new way of creating modern art.