If the LBS had measured Fumbles22's post BUT had not told him the size what would you think of the shop.
As someone who'd just take some calipers and measure it, I don't understand the controversy. But to answer your question, I'd assume it was an oversight.
If the shop had asked for payment for this information (which would be credited against a seat post purchase) what would you think?
I would think poorly of the shop and never grace their doorstep again. If it were some diagnostic information, or something that required special knowledge that would be another story, but this is trivial information that took no skills to come by, and a few seconds if that.
Personally I don't go into retail stores and ask for information, unless I'm going to purchase something. I understand that you have to draw a line somewhere. But measuring a seat post diameter?