The way I see it, 29er should refer to two things:

1- the rim width. Yes it is a 622mm rim, but at an 18mm width like a regular 700, you would go with 700x30 or something for 28 inch total, but with 28mm width, you would have to go with something like 700x50, for a 29 inch total. Same rim diameter, different total diameter of tire plus rim.

2-for it to be a 29er, it should have some resemblance of mountain bike geometry, like the Surly Karate Monkey, thats a real 29er