I was watching it on TV and thought it was totally bizarre.. If he's taking the piss then he's brilliant.. It's bordering on whether it's funny or scary..
If he's not taking the piss then you could assume he'll probably be dead in a few years...
Although at the end he turned to Dave personally and took his glasses off, shook his hand and looked like he was being more sincere with him.. So i'm guessing by that he hadn't totally lost the plot..

I had more concern that Tom Cruise was about to spontaneously combust on Oprah, so I guess you can take your pick of celebrity's wackiness..