Citadel is just a market maker. He will execute for a bull or a bear. This "seller" is obviously a bear. The guy/guys from a few months back was a bull.

In any event, they backed off for now because of all the ask hits. The purpose of showing a million on ask is to scare away action, but it ain't working right now, and they really don't want people buying up their air shares 100,000 a pop let alone in one big chunk at 1 million.