My guess is that the algorithm doesn't expect to make money out of that particular order, but rather guesses this is a bigger order that is being split (laddered if you will) into multiple small orders at different acceptable limits.
If the order is coming from a retail brokerage that's a terrible guess - how often do you think someone goes into ETrade and tries to move $20M of GOOG?
Big orders come from institutional investors. Those are explicitly the orders that market makers are trying NOT to trade against, and that's why they try to buy order flow. Order flow is known to come from players who aren't making big orders.