How does Marc Andreessen know that he has no introspection if the doesn't have introspection to evaluate whether he has introspection? How can he discuss his lack of introspection in a whole-ass interview about his lack of introspection if he lacks the introspection to evaluate his lack of introspection?

You're absolutely right! His sentence about not really needing introspection and the right approach being "Move forward. Go." should be read as the Zen koan it is and carefully introspected on. This is the secret of enlightenment. True enlightenment is no-mind: it's not just zero introspection, it's zero of every dualistic craving. Pure action, without anyone being "there" to act: it's about walking the path, not just sitting and reflecting on it.