Quoted from CrazyLevi:

He always says he does it to protect his fellow Pinsider, which is pretty hilarious as he doesn't seem like the most caring type. And ridiculous, as no price cop in the history of pinball has EVER had any affect on the actual selling price of a pinball machine, nor affected the market in any way at all.
The truth is far more banal; it (used to be) fun to be a price cop. You'd pick on someone for selling a $3,000 Toledo, you'd get a ton of upvotes, and a bunch of other dimwits with nothing better to contribute around here would pile on. It was a nice way to pass the time and boost the ego.
Now it just makes you look like a crabby idiot. If current trends continue, a Shadow in gorgeous shape like this one for $8,000 is going to seem CHEAP in a year, like how an IJ in almost any shape would sell for that price in 10 minutes today, whereas a year ago it would have brought out the entire squadron to abuse the seller. Almost every price police thread these days ends with a triumphant "Sale pending" tag and a bunch of officers licking their wounds, praying that it's all a fantasy that some lunatic just spent $9,000 on a Metallica pro, and wondering how the bad guy got away, like Roscoe P Coltrane seeking solace from his basset hound behind the wheel of an overturned Plymouth Fury.
The price police had an AWESOME run, like 10 years of nonstop rule around here. Now their day is done, and it's time to go quietly into that good night, or find another hobby. Like ruining your neighbor's home sales.