Other exchanges already do similar kinds of things. The CME has implied spreads for instance.

It just becomes another arbitrage opportunity. In the case of the CME it always seemed misguided as well. The implication system was complicated and unwieldy and would frequently not provide the best price for your trade.

It seems like it would have been simpler to just let the market itself handle this. I suspect the same is true with the IEX special orders.