I think it may be going too far to say that Thurber invented these words. The OED cites a letter of E. B. White as its first quotation. Interestingly, this letter was from the same year as The Thirteen Clocks, and Thurber was an admirer of White; so who knows? The dictionary also suggests an etymology: a corruption of "satchel", an old slang term for the same thing (although of course, we don't know exactly what "thing" Thurber was referring to).
Guzzle seems too obvious for anyone to claim as an invention, not to mention the fact that it had been used to mean throat in the 17th c.
I have nothing against Thurber, of course. In fact I intend to dig out my copy of The Thirteen Clocks at the weekend and re-read it.