Again, he can’t have any debilitating symptoms now if he is delivering unscripted complex talks, so your speculation is without evidence.
Yes, he can, if he’s in the beginning stages. Besides, of course my speculation is without evidence. That’s why it’s called speculation.
You underestimate what he has been all of his life. He is capable of delivering highly technical and precisely scholarly presentations with no notes, completely off the cuff. He is absolutely brilliant and always has been.
A degradation of what he has been is still more than almost anyone now living can deliver at the peak of their powers.