It seemed to me that EY's point there was not to castigate Rand for not following Bayes, but rather to point out the flaw in ever creating a "closed system":

Science isn't fair. That's sorta the point. An aspiring rationalist in 2007 starts with a huge advantage over an aspiring rationalist in 1957. It's how we know that progress has occurred.

To me the thought of voluntarily embracing a system explicitly tied to the beliefs of one human being, who's dead, falls somewhere between the silly and the suicidal. [...]

The vibrance that Rand admired in science, in commerce, in every railroad that replaced a horse-and-buggy route, in every skyscraper built with new architecture—it all comes from the principle of surpassing the ancient masters.

Moreover, this isn't a "premise". EY is not assuming a premise that Rand (or anyone else) is bad-because-not-Bayesian; he is using Objectivism as an example of what has elsewhere been called "worshiping the finger that points to the moon."