He’s referring to this:
For Field, Mansfield and others on the team, Cook’s indecision was frustrating. “If Bob or Doug ever had a reasonable set of objectives, they could have shipped a car,” says someone who was deeply involved in the project. “They’d ask to take the next step, and Tim would frequently say, ‘Get me more data, and let me think about it.’” In that setting, it was hard to retain talent: engineers Apple hired for the project would grow convinced things weren’t going anywhere and find jobs elsewhere