Thread:ADour/@comment-5504437-20121211043230/@comment-1713281-20121211063438

Because it was given a reality number in a handbook, which trumps all other rules (kinda like when your parents would explain something with "Because I said so")

More so, it's based off of Earth-5311, which was Kitty Pryde tapping in to an alternate universe to tell story. While it doesn't get that detailed in the cartoon, it can be implied I suppose.