We had this exact drama about 3 weeks ago in the SFF community, when a bunch of editors admitted to accepting and paying for submissions from very clearly AI author[^1], which led to some more interesting revelations: there are many Editors in this space that care _more for the premise of the idea shown to them_ than the actual quality of writing.
I have a suspicion this is what happened here too. Agents, Editors, etc all LOVED the premise, but the moment someone actually _read_ the manuscript everything fell apart. We're reaching peak "nobody reads anything any more" where major publishing houses (Minotaur is an imprint of Macmillan, from a quick googling) are losing big money on this.
In terms of addressing the author's blog post though: no, I don't think this is the sign of the end times. The actual sign of the end times would have been for the publisher to PROCEED even after the AI allegations, IMO.
You don't need to look to AI slop for the end times. It's much closer than that: 20 years ago barely 1% of couples needed medical assistance to have a child. Now, that number is ~17%? Sperm counts falling to an average of zero by 2045?
That is a path to extinction.