I would direct the powers to the Wikipedia-page Persona (user experience) and have him read the second and third sections:
Personas are useful in considering the goals, desires, and limitations of brand buyers and users in order to help to guide decisions about a service, product or interaction space such as features, interactions, and visual design of a website. Personas may also be used as part of a user-centered design process for designing software and are also considered a part of interaction design (IxD), having been used in industrial design and more recently for online marketing purposes.
A user persona is a representation of the goals and behavior of a hypothesized group of users. In most cases, personas are synthesized from data collected from interviews with users. They are captured in 1–2 page descriptions that include behavior patterns, goals, skills, attitudes, and environment, with a few fictional personal details to make the persona a realistic character. For each product, more than one persona is usually created, but one persona should always be the primary focus for the design.
If he don't buy facts, I'm afraid you can't win. However, you can use personas without telling him which techniques you use to collect requirements or find flaws. Does he really care if you use Notepad or Visual Studio when you create web pages? If not, would he need to care on the use of personas or not?
