I don't see these as being all that opposed to each other; or, put another way, I see no reason why narrative and character-driven play can't take place within those Gygaxian constraints. All it would seem to require is that the players pay as close attention to time and space constraints as the GM.
Although I think it is right to say that both players and GM can be involved in establishing and upholding truths, there is another vital contrast between the modes of play. That is, whether play focuses on the inner change of the characters, or outer change in the world. Is the trek from Trilus to Pavis about how they change the world? Or is it about how they change themselves? If the latter, then what's mooted is that it makes sense to state truths in the way that they are true for the characters.
On the one hand, how could it matter to state truths in any other way? On the other, it skirts
deciding on behalf of the player characters. Suppose as a player I'm told I reach a chasm too wide to jump. Perhaps I have some ideas about how to jump "too-wide" chasms? Being told it's too wide might seem disempowering, but ought I really be focused on my character's ability to jumpt a chasm (an external fact)?
A related issue exemplified by the Wand of Secret Door Detection perhaps isn't the consistency, as what it decides for my play. Suppose Jo's WoSDD finds no secret doors, but later on Addy's search reveals one. How must I as Jo feel about that? To what extent are external truths expected to impinge on me. I might feel I need to respond in some way - "This wand's no good, I better find that morokanth who sold it to me and... " and in a sense that's perfectly fine - we are off on another tangent. In another way, it seems potentially distracting and dissonant without much pay off.
Perhaps then one way to value consistency is in getting things out of the way and leaving what happens up to the player. Facts are settled rather than continually revisited. It can be useful to overturn supposed facts in the interests of challenging character commitments - but usually not for
every fact.
My experience has been that what participants say - our established truths - gradually make the world we are authoring a shared space that we inhabitant, filled with things we're interested in. But what is this shared space, really? As a space woven of words it is symbolic and analogic. That which seems without is in fact within. However, when established in common it is all too possible for one author to continuously submit facts that really are
without. They're imposed on other participants. This is the risk with preestablished fiction and over-emphasis on a putative consistency: from whose viewpoint? Consistent with what.
Thus, I read the OP and the earlier thread it relates to as advocating consistency with the inner world of all participants, which can be approached by thinking about each imagined truth in the way that it is true for the player characters. In a sense, submitting each candidate truth to the test of how it matters or will come to matter to all participants. I don't see that as antithetical to consistency in the sense of established truths normally being upheld. Nor ought it be antithetical to saying enough about each truth that players can decide what their characters do in its relation.
In summary then, for me one lesson from the OP is the picturing of each imagined truth in the way that it is true for the player characters. In that way
character > situation > setting conveys the meaning that the situation matters because it matters to the characters, and the context for that situation - the setting - matters for the same reason. How else could it matter?
What then of the GM? In many of the games concerned, truths are categorically divvied up. GM is frequently required to create oppositional and catalytic truths. Torchbearer 2 puts it well
Descriptive details are nice, but keep in mind that the primary responsibility of the game master is to place problems in the paths of the characters. Without challenges, characters will never grow and change.
Here one sees that the truths collectively form a matrix upon which transformational-truths - the narrative of inner change of the characters - subsist. Contingent truths and those that are fluid, can only contingently and fluidly justify the transformational-truths subsisting on them. If I find out tomorrow that my WoSDD doesn't work as expected, then tomorrow I am forced to revise that truth
and other truths that depend on it. And what is meant by "collectively form a matrix" is that atomic truths are not the only truths we are interested in: we're interested in meta-truths that lie atop them. Things that are true in virtue of the truths they subsist on. This creates space for multiple authors to submit truths, and in the group consenting to accept and uphold them for those to sustain their purpose of play. A final caveat comes to mind: no imagined truth is ever complete. The WoSDD might have properties as yet unrevealed.