Today, there is still a 122% short position on Gamestop. There are still many funds hedged against GME. Melvin might have had one of the larger positions, but there are many more funds with this position. Source: https://finviz.com/quote.ashx?t=GME
As you say, they would make money by running the orders, regardless if GME goes up or down. So - why would they stop? It is most likely that Citadel is still exposed to other funds holding short positions in GME.