I don't see how this Cthulhu example, as described, is either small-g or big-G gamist.
The gamist solution would be to try and invoke mechanics into this scene ASAP, wouldn't it?
From the post you quoted:
I’m one of the GNS faithful, I have a little shrine to Ron Edwards in my room and everything.
By "gamist", thefutilist means the same as what Ron Edwards does here:
The Forge :: Gamism: Step On Up
The players, armed with their understanding of the game and their strategic acumen, have to Step On Up. Step On Up requires strategizing, guts, and performance from the real people in the real world. . . .
The in-game characters, armed with their skills, priorities, and so on, have to face a Challenge, which is to say, a specific Situation in the imaginary game-world. Challenge is about the strategizing, guts, and performance of the characters in this imaginary game-world.
This has nothing in particular to do with rolling dice. As Edwards goes on to discuss,
Challenge is the Situation faced by the player-characters with a strong implication of risk. It can be further focused into applications, which individually tend toward one of these two things:
The Gamble occurs when the player's ability to manipulate the odds or clarify unknowns is seriously limited. "Hold your nose and jump!" is its battle-cry. Running a first-level character in all forms of D&D is a Gamble . . . More locally, imagine a crucial charge made by a fighter character toward a dragon - his goal is to distract it from the other character's coordinated attack, and he's the only one whose hit points are sufficient to survive half its flame-blast. Will he make the saving roll? If he doesn't, he dies. Go!
The Crunch occurs when system-based strategy makes a big difference, either because the Fortune methods involved are predictable (e.g. probabilities on a single-die roll), or because effects are reliably additive or cancelling (e.g. Feats, spells). Gamist-heavy Champions play with powerful characters is very much about the Crunch. The villain's move occurs early in Phase 3; if the speed-guy saves his action from Phase 2 into Phase 3 to pre-empt that action, and if the brick-guy's punch late on Phase 3 can be enhanced first by the psionic-guy's augmenting power if he Pushes the power, then we can double-team the villain before he can kill the hostage.
The distinction between Gamble and Crunch isn't quite the same as "randomness;" it has more to do with options and consequences. Fortune can be involved in both of them, and it doesn't have to be involved in either (see Diplomacy for a non-RPG example).
The sort of CoC scenario thefutilist describes is "gamble" if the players don't know the conventions for asking and answering question that the GM is following, and hence have to ask questions essentially randomly, poking in the dark hoping to get the information they want before they declare an action that self-destructs the whole library, or brings the cultists swarming in, or whatever.
It is "crunch" if the players are able to ask questions in a systematic fashion, understanding the conventions that govern the way the GM provides answers. Thus, a bit like Edwards's example from Champions, the players can home in on the information they want -
which book has the ritual in it, and what does it do? - while avoiding producing consequences that they don't want - inadvertent summonings, swarming cultists and the like.