The idea that processor evolution is blocked by the need to run C code is wrong. We had many alternative designs, both for languages and also for processors. They were simply not successful. I still remember the pain of segmented memory in 286. Also much of the criticism in the article would apply to von Neumann / Harvard architectures in general, and is not specific to PDP-11 and C.

Then also, where new programming methodologies such as CUDA are invented to allow new processor designs, it turns out that they can be quite successful despite moving away from C. But then it also turns out that this programming model was actually not that great to program in, and people try hard to move back again by making the hardware more capable.