I think attributing all of his flubs/incoherent sentences/whatever you want to call it to either JUST old age or JUST a stutter is wrong. Its a mixture of both. Personally, I believe I have a seen a few times where he's had a weird sentence that its pretty clear to me its a stutter. But some of his mistakes are also just mistakes you can't really blame a stutter on. But its definitely one part of it