Maybe, even if Linus noticed the Hurd, he would have started Linux anyway. It would have been legitimate, so please stop with this issue.
He knew. This is a quote from his emails with Tanenbaum, back in 1991:
If you write programs for Linux today you shouldn't have too many surprises when you recompile them for Hurd in the 21st century. As has been noted (not only by me), the linux kernel is a minuscule part of a complete system: full sources for Linux currently runs to about 200kB compressed - full sources to a somewhat complete development system is at least 10MB compressed (and easily much, much more). And all of that source is portable, except for this tiny kernel that you can (probably: I did it) re-write totally from scratch in less than a year without having any prior knowledge.
The full exchange is part of "Open Sources", published by O'Reilly, as well as somewhere else on the net; I don't have it handy, I only quote this fragment in my talks about the origin of Linux and that's what I have handy.
/alessandro