Without looking it up - there is also a connotation of goon as embodying silliness, perhaps even innocence, as well as largeness, stupidity, obedience, awkwardness, and such thuggish attributes. Gooniness must precede your book by decades. I recall also an aircraft affectionately known as the "Goony Bird," putting it at least 60 years ago, and the term must have antedated that, too.

"Thug" is another word with a nice pedigree, by the way.