Do you know any further details on his departure from StackExchange? I saw this message on his profile:

> I do not participate on this site any longer, except to respond to comments regarding my own text, if that text is unavailable in another form. I do not accept the political moderation atmosphere here, it is not compatible with open science.

It seemed like he really enjoyed helping people on the site, and there's nothing (left) on meta to show that the situation for him was deteriorating