They probably declined because they probably didn't want to be affiliated with a terrorist kind of show? I dono if they even looked into the anime...

Anyways... I remember seeing a Cheese-kun keychain in the 1st episode where the person was snapping a photo of when Kallen and the other OotBK crash. Cheese-kun is copyrighted by KFC (who owns Pizza Hut, I believe) so I'm wondering why he's still in there, but I'm glad he is!