No, if you read the entire context of the discussion in the book you'll see it's the same one. And you're wrong to say that there is not a gravity well if you do the experiement in deep space. One twin undergoes acceleration to change direction and by the principal of equivalence that is indistinguishable from a gravitational field.

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"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind." - William Thompson, 1st Baron Lord Kelvin

"If it was so, it might be, and if it were so, it would be, but as it isn't, it ain't. That's logic!" - Tweedledee

This isn't right. This isn't even wrong. - Wolfgang Pauli