The only reason I can find that he gave was "I resigned because I could not be an effective leader under the circumstances"; I don't know what unrelated reasons you think he gave, although if you want to share a link, that'd be great. Mozilla's own blog post about his resignation was "Mozilla prides itself on being held to a different standard, and this past week, we didn't live up to it." It's super hard not to read all that as him being asked to resign, and CNET's rather long autopsy article on it says that the board wanted to offer him another position but he chose to quit everything. (That article also says that there was a lot of doubt about whether he'd make a good CEO for reasons entirely unrelated to this; he was known for, as a Mozilla Foundation director put it, having an "inability to connect and empathize with people.")
The Board didn't defend him publicly. I think, when a Board fails to publicly support their choice of CEO in face of a controversy, for a CEO that's basically a form of constructive dismissal.
Yes, exactly. That’s what I was trying to get across by quoting Baker not defending him, and what “asked to resign” means. I generally don’t complain about HN downvotes, but it’s more puzzling to me than usual — do people think I was saying Eich wasn’t fired? [shrug emoji]