I am a Mozilla employee, but I have no first-hand knowledge of what the board did. In Mozilla town hall meetings, multiple board members said they pleaded with Brendan to stay. I don't think they or Brendan would mislead us, so perhaps Brendan is using a very precise meaning of "tried to convince me to stay as CEO."

He does not know otherwise and is mistaken. When Brendan's comment dispelling the rumour that he'd been offered to remain as CEO it was brought up in the Mozilla governance newsgroup and other places. Mitchell Baker clarified that he was not asked to stay on as CEO but was asked to stay on in another, lower level, position. Unfortunately some employees still repeat the false claim.

Why the downvotes? cpeterso's comment (a Mozilla employee) seems to agree with this.