Well, even THAT could mean that the SLS does 6-10 flights without competition. Starship is still far away from even just being an overcomplicated BDB. And a manned version is not even in mockup stage. As funny as it sounds: Should NASA wait for SpaceX?
Well, they selected SpaceX Starship as the HLS that will land the astronauts on the moon, so they are going to be waiting for Starship regardless. Their plan B for HLS is Blue Origin, which is even farther away from flight testing of manned versions. Once Starship is sorted out, Superheavy should be an experienced flight booster, so yes, maybe NASA should just kill the SLS boondoggle and just wait for the much more advanced yet simpler Starship architecture to go to the moon instead of wasting more on the kludged-together Artemis architecture.
SpaceX does a pretty risky gamble there since they essentially stopped all Falcon 9 evolution in favor for Starship. Not really smarter than what congress wants NASA to do.
Falcon 9 was developed to the point that they are reliably and repeatedly flying a fleet of boosters, some with dozens of flights (the record is 18 reflights IIRC). They are not following the disposable booster paradigm anymore. It's rather like saying that the USAF stopped all B-52 evolution in favor of more advanced bombers. That is quite true, but B-52s are still flying and fulfilling missions in parallel with its more advanced progeny.
Falcon 9 is flying pretty close to weekly which is a remarkable cadence, and the claim is that they can fly each booster 10 times without refurbishment, with a lifetime of 100 launches. They have something like 16 boosters active in the fleet and are still building new boosters as needed. So there is potential for up to 1600+ launches with existing hardware. That is over 30 years worth of missions at current cadence not even counting the new boosters. Falcon 9 might become the LEO equivalent of the C-130 for getting cargo to orbit.
I'd argue that if they can get Superheavy/Starship flying, then yes, it would make much more sense to wait for that than for NASA to toss $2 billion into the ocean after 8 minutes of use on every mission, especially if Starship is already needed to bring them to the surface. If they are going to spend that sort of money, I'd rather see it invested into reuseable, less expensive launch systems that are the way of the future than to see it thrown at 1970s disposable tech that is at an evolutionary dead end.