Will my friend be able to find work if he doesn’t care about the anatomy of his job?

Finding work and getting work done are very different things.
Success in jobseeking is a function of pretence: people skills, credible mien, ability to make one's achievements and skills look superior, competition.
Success in actual work varies per job and available assets, personal and the company's. A skilled manager can get almost anything done, provided sufficient, well picked and motivated staff. A skilled "superuser" (as your friend sounds like) is aware of the tools of the trade, adept in their usage and possesses heightened senses for tinkering without reinventing the wheel, and as such can get most tasks done with relative ease and haste. An expert accumulates a diverse and profound knowledge of a field (or subset thereof), and is unrivalled in both mien and determining the nuances of said field, but this specialisation takes a long time to learn, and doesn't always help in practical matters beyond providing guidelines.
Regarding massaging, there's not really that much reliable theory as far as I'm aware; if he's good at it and can get people to open their wallets, it's viable without having academic knowledge of human anatomy. A school is just for having ready access to expert guidance.
Audio production is a broad area of definition. However, globally it requires a certain imagination, bearing a clear vision of the kind of sound one seeks to reproduce given available (limited) instruments. All the theory in the world cannot create this (otherwise computer generated music mightn't be so damn awful), it can help refine it and provide a common language with other folk in the business.