The Designer Gives the Client a Pitch
More so than any other member of the team, the game designer is called upon to "pitch" the concept of the game to the client or sponsor. It's not a pleasant duty, but often, the designer is the best qualified to do so.
Delivery of a pitch is done in the context of a negotiation - you are attempting to get something you want (generally, funding), and the game is the reason you present for obtaining it.
The author goes on for a bit about negotiation and salesmanship - it's a random collection of tips, not very well presented. There are better resources for this information.