I hate Nvidia, and will never buy their products, but, I agree with his unstated premise - x86 doesn't work except where there's no real competition.
On the desktop, you need it, because there's really nothing else around. POWER is nice, but where are the apps you'd want to run? Maybe ARM will challenge in the future, from the bottom up, but for now, they don't.
But, trying to move the miserably inefficient x86 instruction set to platforms that need efficiency and don't care much about compatibility puts them at a huge disadvantage, and an unnecessary one.
They could be very competitive if they started from scratch, but the penalty of using x86 leaves them non-competitive.