In this speech on the history of Linux from 2001 [1], Linus makes it clear that he views the viral nature of the GPL to be a crucial component of Linux's success. He likens it to allowing evolution to take place. I'm not sure when this viewpoint took hold for him, but it would suggest that he likes the most fundamental part of the license (though he disagrees with much of the politics).

[1] https://www.youtube.com/watch?v=WVTWCPoUt8w