It isn't really. The assumption that these companies aren't hiring any infrastructure engineers is absurd. They all have massive in-house teams doing GPU optimization and everything else that the author brings up. They just don't need an external consultant for it.

He didn't say they aren't hiring _any_ but that they are hiring few and that he finds it strange that despite his multi-decades record of squeezing performance on the gpu-software stack he isn't getting much collaboration proposals.