Does anyone know why AZ state regulations prohibit seed companies from shipping this seed to the state?
Hm, I don't know, but I recently planted seeds of the cypress vine (Ipomoea quamoclit) which has a similar type of flower. The foliage is more feathery though. It's doing really well in a pot with a trellis. I'll post a picture later. That might be a suitable substitute for you if you can't get the one you like.
As I understand it, the Cardinal Climber and Morning Glories were outlawed in Arizona due to the fact that they would spread (via seed presumably) to the local cotton fields, sprout and take over. Thus diminishing the cotton crop and gumming up the cotton harvesting equipment. An outdated law for sure.