Where else would it come from? It’s just using the normal meaning of “to grok” [0] (or its present participle), which is a well-known term of hacker jargon [1].
These definitions feel somewhat limited, compared to the jargon file entry[0]
grok: /grok/, /grohk/, vt.
[common; from the novel Stranger in a Strange Land, by Robert A. Heinlein, where it is a Martian word meaning literally ‘to drink’ and metaphorically ‘to be one with’] The emphatic form is grok in fullness.
1. To understand. Connotes intimate and exhaustive knowledge. When you claim to ‘grok’ some knowledge or technique, you are asserting that you have not merely learned it in a detached instrumental way but that it has become part of you, part of your identity. For example, to say that you “know” LISP is simply to assert that you can code in it if necessary — but to say you “grok” LISP is to claim that you have deeply entered the world-view and spirit of the language, with the implication that it has transformed your view of programming. Contrast zen, which is similar supernal understanding experienced as a single brief flash. See also glark.
2. Used of programs, may connote merely sufficient understanding. “Almost all C compilers grok the void type these days.”
Thank you for sharing this! I used to use Grok incorrectly before reading Stranger in a Strange Land and now lament that the intended meaning is so poorly understood. While I can appreciate the irony that people don't grok grok, I guess I have to acknowledge that language evolves and generalizes, and not even Heinlein, providing a fairly original word and concept, is exempt from that effect.
The Foldoc entry is actually from an older version of the Jargon file. Foldoc used to be an expanded version of the Jargon file, maybe that has somewhat become reversed in the meantime.