Stan,
Like you, I am suspicious of anagrams and I am not at all convinced that the one I presented was intended by VN. I should say, however, that Alex Roy's point was that the "contextual evidence" is found in the fact that the index entry for Gradus points to the note to line 12, which contains no explicit reference to our automatic man.  Also, you quibble with the spelling of "loony," but my spelling is also VN's:

"You must help us, Mr. Kinbote: I maintain that what's his name, old--the old man, you know, at the Exton railway station, who thought he was God and began redirecting the trains, was technically a loony, but John calls him a fellow poet" (238).

Shade refers to God as "the big G" and Kinbote, in the note to his Index, says Gradus is represented by a capital G. So could this correspond to "see Gradus, loony thing"?

Matt Roth