OR

It could be due to the fact he never said he was talking about a 3 piece wheel.

OR

The fact that it isnt common/I have never heard of anyone doing a spacer where he is talking about.

Being a "wheel guy" the bottom line is wheels are not designed to have a spacer there. I would never recommend doing this. It hasnt been tested and wheel safety is not somehting I would mess around with. I have installed/sold/taken apart plenty of wheels and not once have i heard someone doing this.