> That is simply not true.
Yes that is true, as shown by the link I provided. Methane/LOX is simply one of the go-to options for liquid fuel rocket engines these days, whether or not these engines are intended to go to Mars or not.
And btw. SpaceX themselves market Startship as a transport vehicle "to carry both crew and cargo to Earth orbit, the Moon, Mars and beyond." https://www.spacex.com/vehicles/starship/
> the only current realistic shot at our species being multi-planetary.
I'm curious: How does building a base on Mars, that is 100% dependent on regular support from Earth to survive, contributes neither resources nor self-sustaining living space to our species, cannot terraform the planet, and cannot serve as a backup in case Earth goes boom, make our species "multi-planetary"?
A multi-planetary species has permanent settlements on more than one planet or moon, that are either self-sustaining, or contributing (resources), or both. These settlements serve a role beyond bragging rights and exploration. A Mars base, insofar as we could currently make it happen, doesn't do that.
If a 15th century nation brought 5 guys to some bare-rock-island in the middle of the Atlantic and left them there with the promise to drop by every now and then to bring them food, that doesn't make them a colonial power.
> free of NASA's hope-ending bloat
Funny that you mention NASA, because they actually do have a plan to make humanity multi-planetary: https://www.nasa.gov/feature/artemis/
Other than Mars, the moon is near enough to actually make permanent bases feasible, which could provide a platform for further space exploration (Launching something from 1/6th of earths gravity uses a lot less energy). Luna is near enough to support a colony, including rotating crew, and it actually has a resource that could become useful in the not-so-far future, that could be worth exploiting: https://en.wikipedia.org/wiki/Helium-3#Moon