Calling someone a sheep is a metaphor. When you think of 'complacent' what animal better fits it than sheep. It is a very commonly used turn of phrase because of this.
He is saying that sometimes you are sheep and sometimes a herder. It isn't an exclusive or.
In life, you want to be a craftsman but you sometimes just need to be a tool. Many times, you have to be both to get the job done. For CEOs are tools to their customers, and that's just how it works.
