I would disagree with this point, but note that I used the word deceptive and not dishonest. Though I do believe that you have something to gain by doing a manual clearing in that the exchange has reduced risk (this should not be disregarded, as risk is used as a financial instrument), my main point is that the trading range on the site and the definition of a trading session led many users to believe that they would at least have some time to react to >10% market moves.
I think what he has to gain, and what has motivated this, is much more obvious: if BTC price has significantly moved then the trading ranges are old (either no offers or no bids are left) and no trading happens. He's losing out on a lot of potential fees from trading (fees aren't low), and hence waiting 12 hours or so is too expensive.