Well, he's certainly right about Artemis being a very inefficient architecture, but he's probably coming from wanting SLS money for himself and not the 20x Starship launch per 2 person visit.
In other news, Elon is taking a lot of heat for suggesting US should deviate from its 'Moon-to-Mars' plan.
Going straight to Mars is certainly a great way to lock in more money for longer and shed themselves of the baggage of having to get Starship HLS working in 2 years.