IDK, I think the convo is hard to have without explicit goalposts.
For context, the original quote was:
* > How about understand the OS internals? How about write a compiler? How about write a library for their fav language? How about actually troubleshoot a misbehaving nix process?
Writing a compiler, writing a library for their fav language, and troubleshoot a misbehaving nix process are all examples of things I would definitely expect a CS major to have done at some point.
A SoTA compiler for Rust or whatever? Ok, no. But, you know, a compiler.
Ditto for library -- better than the standard lib? Ok, no. But, you know, a standard lib that's good enough.
ditto for debugging nix processes. Not world-class hacker, just, you know, capable of debugging a process.
I guess the other examples in that quote seem to suggest that "OS internals" probably means something like "knowledge at the level of a typical good OS course".
And who knows what those people meant by "comfortable interacting with operating systems in any depth". There could also be some reverse D-K effect going on here... "I got a B- in CMU's OS course" still puts you very well into the category of "understand the OS internals", IMO.