No one said that. At the time there was a massive gaping hole in the OS market begging to be filled. OS vendors were gouging everyone, and GNU/Hurd kept experiencing delays.
Version 6 Unix was about 9000 lines of code; the first version of Linux was something similar. Firefox has 27 million lines of code. Linux has about that now, too, which is why one reason you don't see grad-school Linus #2 writing an OS and getting traction.
Did he write a blog post (or newsgroup post) in advance of writing the first version? I'm all for pet project tinkering, but seems strange to publicly make a pronouncement before starting. There's no "news" here, why is it on the front page?