Randy, I'm not familiar with what Triad suggests, but it's very likely that you've interpreted it correctly, i.e. one-third of the way in from the side wall. It doesn't strike me as a universally superior location. For example, with two subs the paper by Dr. Toole's people at Harman(which I believe you've read)suggests center of side walls or center of front and back walls as being good locations for the two. Right in the corner is still a good spot for a single sub unless the room is nearly square, which might make that one-third out location better.
