If this really was his personal decision, then he would have written the press release, and the chairwoman would have issued a press release expressing support.

that's if they were aware he was leaving. occured to you he might just have sent and email, published a blog post and left? ;-)

He might have thought that it was strategically better for him personally to step down instead of actually being fire, but no one believes that this was just his personal decision. He was forced out under duress.

Yup, but the decision he probably had to make was to save face and leave or get booted the fuck out.