That's the same philosopher who thinks we live in a simulation. They're about as credible as their profession is respected. I'm fairly certain I'd disagree with him in the piece of writing he next pens as well.
No, he believes that one of these three things is true:
1. "The fraction of human-level civilizations that reach a posthuman stage (that is, one capable of running high-fidelity ancestor simulations) is very close to zero", or
2. "The fraction of posthuman civilizations that are interested in running simulations of their evolutionary history, or variations thereof, is very close to zero", or
3. "The fraction of all people with our kind of experiences that are living in a simulation is very close to one."
Furthermore, reality itself is the "simulation". It takes the entire universe at one time t1 as input, transforms it according to the functions known as the fundamental forces, to produce the entire universe at time t2 as output, where t1 and t2 are one discrete time step apart. Restricting the "simulation" on a subset of the input is bound to introduce errors.
Yes. He has no basis for that belief. The three points you've raised in clarification on his behalf are neither mutually exclusive nor exhaustive over the entirety of the probability space. He is pulling "very close to" out of thin air, in complete disregard for rigorous evidence borne of the scientific method.
