Ian Levi can't be too sick if he's taking on a job like this - he did say he wanted to concentrate on his particular skills in developing new companies.
Can't imagine he'd take on a dog after his long involvement at AGM. Apparently the nickel discovery at DGR is very similar in composition to that at Avebury.
Pure speculation as to why he is really leaving AGM, but it doesn't seem to be "his health"