It seems like a reasonable opinion to me. Looking at the list of what's in coreutils, I don't see anything where performance would be a huge issue other than p

It seems like a reasonable opinion to me. Looking at the list of what's in coreutils, I don't see anything where performance would be a huge issue other than perhaps dd, so any performance edge Rust might provide seems moot. And I would guess that Golang would be less code and faster to write/implement. I would feel differently if it were something else, like gawk, for example. Rust would be a better fit there.