It does look like this latter information is correct. Somehow things are confused on the Escapee site. Today, they have published a retraction of the article citing a Policy 13.2.3 that was supposedly issued October 10, 2014. But, an RV Arizona blogspot post says that policy document is a 2004 agency memo. Which leaves the question as to why the Escapee Rver was cited a few months ago.
This whole issue was created by Arizona officials citing an RVer for filling at the "wrong" pump. Obviously, the real concern here should be directed at that level. And the Arizona representative who gave the wrong information to a valid question.
On edit: and now it looks like the "victim" really was a commercial enterprise involved in racing. Yep, they are not exempt. I do know that if you have any markings on your RV indicating commercial intent you are a commercial vehicle. This has been an interesting adventure.