Folks, whats the real reason? Like him, you don't say it either. His back or what?
I know there is talk about health, but I don't have any information.
Nobody has any information, and that's the way he wishes it to be.
Age, back troubles, arthritis etc. are all good reasons for not touring.
There may be some other issue, additionally, that makes playing difficult for him. We will never know, unless he chooses to talk about it.