When did it become "impossible" for it to happen? Wasn't it left ambiguous when Buckmaster asked the team [0], and kind of likely given the timing and both of the proofs being based on Diego C´ordoba and Luis Mart´ınez-Zoroa's work?
Anyways, I'd say this is more about AI Companies not being nearly as interested in scientific progress as they are in marketing (who would've thought?) than anything else. This also disregards Diego C´ordoba and Luis Mart´ınez-Zoroa's multiple years of work on the subject.
[0] https://cims.nyu.edu/~tristanb/statement.pdf (page 3)