He's nearly 70. Doing a TV show with 20-odd episodes a season isn't easy for those half his age. I think I remember reading somewhere that he said he didn't really get the humour of the show either, so he's putting in long days and there is a disconnect with what he's helping produce. Add in he doesn't get on with the former boss it's not that outlandish that he considers it a mistake to have taken on the job in the first place.
Of course it's all in the way you say it.