Think of it is lazy evaluation. The rules are all known, but they are not evaluated until needed. If we have one single person, how hard would it be to simulate every single input to that one person? You wouldn't need to simulate an entire universe to do that.
Going back to what the author had to say, you wouldn't have to simulate the state of every atom at every time. You only need to simulate when it is measured. Interestingly, this syncs up with what we know about the quantum world where measurement causes the state of the wave function to collapse.
Additionally, the author seems to assume the universe exists outside of himself. He seems to trust the measurements and insights of scientific facts I doubt that he has confirmed via his own observation. Even if he did confirm all of them, this still doesn't prove the universe exists outside of what he directly observes with his own senses.
By analogy, imagine you are a character in a video game. The video game doesn't render the entire universe of the game. Only the portion of the game the character is in at that moment. From the character's point of view, the laws are consistent. The character could even try to postulate some universal laws. Try to determine the size of their universe.
I am not saying the philosophers are right or wrong. I'm just saying there is a lot more to the philosophy than the article covers.