I think he means more "the outer layers".
For instance Alpha Go was written in Python at the outer layers. The core pieces doing the actual neural net work are low level libraries.
Similarly, google search, at the outer most layers, is javascript, then probably some layer of Go or similar, but then the core is highly tuned C++ and assembler.
Similarly, google search, at the outer most layers, is javascript, then probably some layer of Go or similar, but then the core is highly tuned C++ and assembler.