A character looks at the ceiling and asks "Are there any cobwebs?"
The GM needs to provide an answer. Unless the GM's notes indicate cobwebs, the GM has to answer "no" - because principle 3 forbids the GM from adding to the imagined world non-diegetically.
The same would be true for the farrier, discussed upthread.
If the GM is forbidden, during play, from adding to the fiction non-diegetically, then the setting becomes extremely thin. Probably implausibly so in many cases. That is part of what makes the principles demanding.
Likewise the GM can't introduce an encounter because it "seems right" or even "makes sense". The GM's change in the fiction must be for a diegetic reason - map-and-key handling of encounter generation is the obvious example. It's not clear to me how standard random encounter tables would fit within the principles.
And principle 4 is also demanding. Eg suppose the player has their PC, who is fast and strong, open a door. The GM consults their notes, and sees there is a goblin behind the door. The GM narrates the goblin, and a door behind it on the other side of the room. The player says "I stop it before it can escape!" - and so the GM calls for an initiative roll. The goblin wins, and the GM narrates the goblin running across the room and through the other door - that is, they take their full 6-second turn while the PC just stands around doing nothing. Why can't the PC, who is bigger, faster and stronger than the goblin, try and run and/or jump and grab it? Principle 4 rules out as an answer "It's not your turn yet". But what is the in-fiction reason, that flows from the established circumstances and causality?
Some of those things that you describe the GM doing don't seem to conform to principle 3.