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.