What exactly are "real businesspeople"?
Personally I learned a long time ago that there's no business book that can tell me how to run my business. You read some good, some bad and if you're lucky find a few good pearls of wisdom along the way.
It's a variant of the lifestyle business epithet.
He's a business school type, so this rankles. His whole world view is based on broadly applicable business practices, grounded in theory and hypothesis, backed up with data.
His kind of "business person" doesn't even necessarily start one business, even if they might see opportunities everywhere — they get brought in as management. But if they start one, they're probably going to start more.