Linus didn’t write Linux for GNU, though, he wrote it as a response to Minix which, if memory serves, was written by one of his professors and took a hard minimalist approach for teaching purposes and Linus wanted to make something actually practical.

Hell, it had to be adapted to work with GNU (or GNU adapted to work with Linux, I don’t remember which) so, if GNU’s absence meant Linus didn’t write his kernel, it would have been a very indirect result