You should be able to get it as a corollary of the lemma that given two disjoint convex subsets U and V of R^n (which are non-zero distance apart), there exists an affine function f on R^n such that f(u) > 0 for all u in V and f(v) < 0 for all v in V.
Our two convex sets being (1) the image of the simplex under the F_i : i = 1 … n and (2) the “negative quadrant” of R^n (i.e. the set of points all of whose co-ordinates are non-positive.)
I have no special insight here but boring, cynical common sense suggests the following:
The big difference between now and the pre-ChatGPT era is that Google and a bunch of other massive competitors have woken up and want to blaze past OpenAI. For their part, OpenAI doesn’t want there to be a perception that they have been overtaken, so will want to release on a fast enough schedule to be able to trump Google’s latest and greatest. (Of course the arrival of something marketed as “GPT-5” tells us nothing about the true state of progress. The GPTs aren’t natural kinds.)