That's a mischaracterization of his argument. Essentially the author argues that right or wrong the manifesto is especially polarizing and the engineer has essentially made it very difficult for him to work with anyone else at Google moving forward. Zunger in no way states that he condones, or suggests the action of punching the manifesto guy in the face, he just outlines it as a possible reaction, of releasing a company wide manifesto, which could uncharitably be interpreted to call into question the merits of female and other minority engineers.