As I read the post, she takes the fact of a Hot Big Bang (narrowly construed in the modern sense of a homogenous, hot initial state prior to which vanilla GR breaks down, not as a literal singularity) to be a fact knowable by the normal process of science. Whereas the question of what came before that — I.e. what modified description takes over at higher temperatures yet — is placed in a different epistemic category of forever unknowability.

Of course, for any theory that applies within a certain domain, there’s always the question of what happens beyond that domain (“what came before that… and before that… and before that…?”). But this infinite regress isn’t particularly noteworthy. If I understand her correctly, she is claiming to be able to draw a particular line and to say that we can know things on one side of this line but— even in principle — can never know anything past this particular line.

She certainly understands her stuff. But I respectfully disagree with her conclusions — I see no reason to think that we might not make progress on the question through the normal process of science.