My guess is he's gone. Related or not, in previous versions when you'd click on the link for a retired coach it would take you to another coach or player. Apparently is was not an easy fix, and the resulting action was just to delete the hyperlink altogether. I don't think there is a retired coach section, but it's something to consider, although it would be just another clump of data, used relatively rarely I'd think, in a game that's already swelling in size.