The point was that it's bad for business to raise the price of a comic based on one inquiry being seen as an increase in demand. That is bad business.
My question is how doe we know that the dealer has only had one person ask for the books? I find it rare that only one person asks for a specific book when I am selling at shows. If they do, it is usually for an obscure/low demand independent book. If I have it with me by some chance, I sell it. If not, then when I check at home to dig it out I will inevitably look at the pricing on eBay and GPA just to make sure I am not missing something. Sometimes I have to price it up, and the buyers tend to pay the asking price regardless at the next show.
Also, in RMA's Whitman 3-pack case, the more someone requests a book the more likely I am to double check the pricing on it.