Mochizuki would have benefited greatly from such a co-author, in order to truly prove his result to the community. Except that, from reading the article, it so

Mochizuki would have benefited greatly from such a co-author, in order to truly prove his result to the community. Except that, from reading the article, it sounds like he doesn't much care about proving his result to the community. Don't make the mistake of assigning the motives and values of a founder to a late-career tenured mathematician. According to the article, he doesn't care for travel. It's not a stretch to conclude that he doesn't care to communicate his proof to other mathematicians. I'm guessing he found an argument that was sufficient to convince him (and only him), put it online as a slight concession to his colleagues, and then kicked his feet back. Surely everyone else would benefit from his having a co-author, but it sounds like he can't be bothered, and doesn't care if no one else understands his ideas.