Aren't the Rust binaries significantly larger? Wouldn't that be a problem for embedded system and containers? I'm also sceptical to the whole idea. There are tons of more interesting problems to solve than replacing an stable solution with a new one just because you don't like GPL.
I agree it's not what I would spend my time on, but I guess some people found this problem more interesting than us. I don't see a problem with that. Security vulnerabilities in GNU coreutils are rare but they happen. Also this would make building and editing the tools more accessible.