Throwing money at making a particular rocket do something fast is a disaster waiting to happen. Elon's StarShip is designed for Mars, not the Moon. So its pace of development is set to a Mars mission pace.
There is no way that StarShip can be ready to go to the Moon by 2028. Resounding Period. The lunar version of StarShip is version 3 which has not even flown yet, nor has any version achieved orbit, has not passed a preliminary design review, has not demonstrated and proven the ability to refuel in space, is not man-rated, does not have a crew escape on descent method, etc.
All of those hurdles and many more must be achieved before Starship can take anyone to the surface of the Moon at the Lunar South Pole. Once there Starship must land on a level and smooth pad. The terrain is the most rugged on the Moon, So someone, something has to precede it and create a landing pad, else StarShip is very likely to topple over, killing the crew.
Like it or not, the only man rated capsule capable of lunar mission is Orion; like it or not, the only rocket capable of possibly being ready to go to the Moon by 2028 is Artemis 3; like it or not, the only lander likely to be ready is Blue Origin's Blue Moon v1b.
Jared Isaacman is a common sense guy. On NASA's very limited budget [ think shoe string, massively underfunded for its missions ] he has to pick the least expensive, most likely to succeed method. And since NASA has already let lunar lander contracts to others beside SpaceX, one of them is far more likely to win: Blue Moon, Dynetics' ALPACA, and possibly a Lockheed Martin entry. The best of the 3 is ALPACA which has already passed its design review, but was bypassed by NASA in the original contract.
The major role StarShip will play in Lunar Operations is cargo lifting - its unbeatable, as things stand currently. Lunar lander - not so much.