Liking a diet may be necessary for it to have positive health consequences, as you say, but for most people it’s not sufficient. So it’s probably a mistake to treat “X diet has positive health consequences” as equivalent to “I like X diet” when uttered by most people. (For example, I might be able to experimentally demonstrate the latter and demonstrate the opposite of the former for the same diet and speaker.)
Liking a diet may be necessary for it to have positive health consequences, as you say, but for most people it’s not sufficient. So it’s probably a mistake to treat “X diet has positive health consequences” as equivalent to “I like X diet” when uttered by most people. (For example, I might be able to experimentally demonstrate the latter and demonstrate the opposite of the former for the same diet and speaker.)
I took it as literary allusion in a place where such may not have been suited to something in a literalist genre. Which may count as a mistake.