Who was his idiot advisor (and why an idiot?)
Taylor Dupuy. He was an idiot for having a grad student go all-in on Mochizuki, which even at the time was obviously career suicide.
To be fair, Dupuy is a good guy who is sincere about math research. I appreciate the videos he made on youtube about IUT, among other topics. While it was indeed risky for him to invest significant amount of time on IUT, there was nothing morally wrong with that. Remember, when the initial IUT papers were posted, many prominent people spent time trying to understand them. The problem with the technical detail of the papers, and Mochizuki's uncoorperative stance, only gradually emerged later.
On the other hand, I totally agree that it was a major misjudgement that he let his PhD student put all eggs in the IUT basket. Moreover, he had no plan B when it became clear that it would not work.
Thirdly, Hilado made the mistake of then switching to an even worse advisor (CV, who happens to be TD's wife and is weak in math yet super woke). Hilado wants to do Langlands, something CV is not capable of advising. They will let him graduate anyway.
I think this whole discussion is not meant for us to put Anton down. Many of us have sympathy for him. Rather, his case is representative of a phenomenon that's prevalent in math PhD programs (particularly the LRM ones). Namely, a clueless advisor leading the student to a dead end, yet acting like nothing is wrong. Student then drops out of the scene never to be heard again. Then onto the next student. Rinse and shine. It is this aspect that needs to be discussed.