I can vouch for that: As a programmer, I can generally see both programming AI and general LLM use if it was copy-pasted. I know a guy who isn't a programmer who've used Claude Code to make an app, and things are working, but it's sooo clear even to a junior SE that it's vibe-coded. There's a clear lack of consistency, architecture, maintainability, and general human readability.
However, if the code/text was reviewed and edited by a capable human programmer, it's incredibly difficult to single out what is a product of AI and not.
Actual programmers who understand and can write code themselves who use AI simply as a tool, NOT a shortcut, will produce indistinguishable code. Linus is an incredibly smart and capable guy, and for specific uses, I'm confident in him using this tool responsibly.
(The ethics of AI use is a different topic however...)