Touching the finger to the nose is the gesture people make in Charades to indicate that the person has guessed correctly. I think all he meant was that you were right in your explanation. His other behavior indicates that he is 1. closed-minded and does not listen to other people's ideas, 2. arrogant as a reaction to his own low self-esteem, 3. needs to reinforce his superiority by either promoting himself ("I've worked on much more complicated projects"), putting others down, or nitpicking tiny details that don't matter ("Sam, slow down. Sam, speed it up"). I've had bosses like this, and they can become bullies in bad situations. A hard issue to resolve. He needs a position without much power or influence over others, but where he can feel like his opinions matter so he doesn't have to punish others to feel better about himself.
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You don't need to hide, my friend, for I am just like you.