[root_axis]

It doesn't seem like that would work since all you're doing is locating "I don't know" in proximity to arbitrary locations in the embedding matrix, not actually with respect to the unbounded set of things that don't exist within it.

[nkmnz]

Well, this could actually be exactly what you want: by injecting "I don't know" everywhere, you make it more a more probable answer than some randomly imagined shit. It's basically a high-pass filter: high-probability (a.k.a. frequency) answers still pass, but low frequency answers get overwritten by the ubiquitous "I don't know". Some loss of good (or at least: creative) answers will happen, though.