These are heuristics. They will of course produce false negatives. Given the huge volume of available books relative to available reading time in a human life, the most important thing is to minimize false positives.

Whether the particular books you refer to are false negatives on these heuristics is of course a matter of opinion. I don't know Woodward and Bernstein's book on constitutional law; their most famous book, All the President's Men, would surely fall under a similar exception to biography/memoir, since it is an account of their own investigation.