He felt he needed a break from the unremitting stress and fatigue of a four-year tour, during which, as your diarist notes, he has also written two books.
He was offered an opportunity to work for World Service News in London but declined. His expertise will be sorely missed - and neither Misha nor I would want to give the impression that he is leaving on bad terms, or that he has decided never to work for World Service News again. I certainly hope he will.
World Service News
BBC World Service