How about he retired because:
(1) he signed the BP rights deal Friday night at 8pm
(2) he knows the trial is good
(3) he wants out so that December 1 he is able to buy 50m shares on market as he won't be chairman
(4) he also has already signed a trade deal that will be announced tight after the AGM and trial results on December 15 for 45cents a share
Merry Christmas!