I believe the author picked the cross hatched texture background to match the rest, as well as the font and the muted retro green and orange-red, so it's not like it was a mere copy/paste job, either. More like (apart from the name pun) Austin Powers is just another ingredient, like the colour to paint with, the texture, the font, etc.
Further--this is a personal belief so take it cum grano salis--if one releases a blockbuster film, one of the (intended!) effects is having its iconography engrained in the public's mind and culture. Saying you cannot use imagery that has been force-fed into the public consciousness at all, is like getting hit by a fire hose and being told you're not allowed to drink or wash with the water. And I had this thought, having to fear being punished for using a certain icon to communicate your ideas, is a lot (but not exactly, I do hope you can see the similarities though) like what the Danish cartoonist had to fear when drawing Muhammed. (let me repeat: there's a lot of differences between the situations, but also an eerie similarity)
Anyway, it's a really great library, I'm looking forward to having an excuse to use it.