Yes, having trusted people in your command staff is bad. Based on this line of reasoning, Kirk should have transferred his entire command staff off the ship long before STII: The Wrath of Khan. Huh? Since when did Kirk do the logical thing. While Spock was suggesting chess and Checkmate, Kirk was playing Poker and bluffing in The Corbomite Maneuver. Remember the odds of success dialog with Spock in Errand of Mercy? No, Kirk doesn't believe in a no-win scenario. Spock, following correct logical decisions in The Galileo Seven, repeatively failed.