Well, he's not wrong technically, but the context feels like it's obviously missing. We have no Saturn V vehicles anymore, nor can we build them again. Starship might require that many launches to get to TLI, but with reusability, it probably can. Not to mention that the cost will come down a bit. So it can at least do it soon.
I'm sure others have more coherent and thought out rebuttals.
SLS is very expensive, but so was Saturn V. If all goes well we should have multiple providers that can provide SLS-like services more cheaply by on-orbit refueling, but until then we should keep SLS in production. It’s here, development is complete, and it works.
Because a lot of "Released Engineering Documents" were just engineering notebooks, and each vehicle was different, even the parts that were supposed to be the same. There was a lot of "repair" versus "rework" disposition, and a "Just make it work; it only needs to work once" culture.
Basically, because it was a race against the Russians, and the Russians were winning.
The production lines are shut down and any custom tooling has had its materials reclaimed to make other things. The institutional knowledge, the little bits that never got written down in the blueprints or manufacturing instructions, it's all gone. The people who worked on that rocket and its components are dead or have been working on something else for the last 50 years. How well would you remember some little tidbit of information that you last needed half a lifetime ago?
Because it is based on obsolete technology. You wouldn't want to build a flight computer with hard-wired (as in literal wires) software, would you? A lot of it would also have to be reverse engineered, to the point where you might as well build a new vehicle.