Artsy fartsy people do. This film is a special type, and it's also almost 40 years old. Apparently photographs taken with this film have a certain look that artsy fartsy people like, so they're willing to pay a lot of money for it. My roommate is selling it to some guy in the UK, and he doesn't want to take a chance that someone will accidentally x-ray it. He's already got "Film: Do Not X-Ray" stickers all over it. He just wants a little bit more assurance that it won't get ruined.
Thanks for the info, guys.