This thread raises a more general problem in that bids and asks need to chase the peg level as BTSX price changes. As the OP suggests, this can mean one is pushed out of line when the price moves, and prioritisation for shorts is given to whoever is online when a buyer over the feed price price happens to turn up. Also, because each order cancellation and replacement costs in fees, it is uneconomic to change orders as the price moves (especially if BTSX is rather volatile), meaning that the market is less dynamic and efficient.
So is it theoretically possible to introduce an order type (or market) where the order is relative to the feed price? It seems to me that down the track when people want to buy and sell USD without reference to what BTSX is doing in price, that's how many will want to trade it. I can imagine there might be some challenges with thinking about collateral requirements and the like.