> Thats, speculation

Its speculation but informed speculation.

> more or less immune to budget cuts because of this

That is true so far but not a law of nature. There are many in congress who don't like it. It touches every state, but some state far more then others. And an alternative solution would also spend money.

SpaceX is in California, Texas, Florida and Washington. And other commercial providers like BlueOrigin are in Alabama and Florida.

Originally it was a Alabama and Florida Senator who pushed SLS. A Florida senator didn't want commercial space, he wanted SLS launching from Florida. However since then every Florida senator will understand that SpaceX aud Commercial launch is 1000x more important for Florida then a SLS launch every year.

So a state like Florida was incredibly pro SLS, now this is no longer true. Alabama and Utah will continue to be pro SLS. However Texas and California (slightly relevant stats) will certainty not be.

There are forces in congress that don't like the waste and Alabama/Utah dominance and when Starship fly's regularly before Artemis 2 even launches you will see some series attacks on SLS castle. And if SLS has any series issues it will be easy to topple. Even just delaying funding for the new upper stage can kill it.

Its a very long time from now until late 2020s. Consider the difference in the industry over the last 7 years. 7 years ago there were still influential voices who thought reusable rockets would never be real, now reusable rockets are so boring that even hard core space nerds don't watch all the launches anymore.

SLS already looks like a flying antique in a few years it will just be comical.

> one, contrary to normal federal procurement rules

Federal procurement rules don't really apply to large NASA missions. As SLS is single sourced right now.

> two, not a sane idea

So then by your own logic SLS is not a sane idea. I guess we agree.

> I'll note, that even a Block I SLS launches 30t more into LEO than Falcon Heavy does, the numbers go up even higher for later blocks, presumably this advantage is even high for lunar missions.

We are not talking about Apollo. This is not a single all-in-one launch architecture. Artemis already relies on multiple launches for all its missions. Anything but single launch payload comparison will come out much better using commercial rocket.

Falcon 9 heavy can launch literally 5-20 times as often while you can launch 20 of them for the price of single SLS launch. 20 Falcon Heavy rockets costing 140M a pop (likely would be less) cost would literally be cheaper then Artemis 1 launch cost alone.

You can also do the numbers for New Glenn, Vulcan, Terran R, Neutron and all the other commercial rockets. Going to a multi launch architecture designed for launch vehicles of current size is sensible, far more so then single source multi-billion SLS.

You could literally pay for 10 years of all launches required with the price of just the Artemis 1/Artemis 2. Its financial idiocy beyond rime or reason and nobody who seriously looks at the numbers can defend it.

There are so many other architecture that could make sense. Even dumb things like launching the Service Module and Orion separately would work and if you did, Falcon Heavy would be totally doable and far, far cheaper then the current architecture. But of course current Orion isn't designed to do that, no-no, we couldn't do sensible architectures like that.

If you actually gave space mission architects freedom from the the political milestones, not a single one of them would ever come up with the current Artemis program.

All of this is before we even consider the existence of Starship. SLS/Orion are terrible ideas BEFORE you even consider Starship. If you consider Starship (and Artemis already has a hard dependency on it) SLS/Orion go from terrible ideas to borderline insanity.