Let's say Professor X reads outdated books or those with inaccurate information, while John Doe reads up-to-date books with reliable information. Please confirm if the phrase what he knows is wrong sounds natural.
Joe: Professor X happens to be listening while I was at the library. He corrected me when I asked the librarian, "Can I borrow books?" He told me that I should have used may instead.
John: What he knows is wrong. Modern usage guides now accept can in informal situations.
Joe: Professor X told us that Einstein failed math.
John: What he knows is wrong. In his book, "Einstein: His Life And Universe," Walter Isaacson wrote about Einstein’s response to the Ripley's claim: “I never failed in mathematics. Before I was 15 I had mastered differential and integral calculus.”