Don't criticize, condemn or complain.
He makes it clear that by "Don't" he means "Never".
A corollary: there are many startups that would never have gotten of the ground if friends of the 'owners' hadn't criticised their ideas. Criticism is informative. It informs you of weak spots you easily overlook, it forces you to explain your idea and think about it much deeper than you ever would if no one criticised you.
Don't condemn or complain: maybe. Don't criticize: that would really be very wasteful.
When dealing with people, let us remember we are not dealing with creatures of logic. We are dealing with creatures of emotion, creatures bristling with prejudices and motivated by pride and vanity.
More often than not, a criticism does not have the intended effect. Our instinct in the face of criticism is to become defensive.