Read the entire history to get a handle on his mindset. He wanted to tinker. Minix helped him get a foot up on the design since it was open. He also wanted others to help.
Free as in libre.
"Linus Torvalds has said that if there had been a free Unix-like operating system on the 386 at the time, he likely would not have created Linux."
You can try to bend the definition of the word "free" all you want, but it's not working.