system
Given the following post, respond as if you're commenting on Reddit:
human
[Thor: The Dark World] - Why did Kurse leave Loki in his cell?

Loki smiles at Kurse as he approaches the cell. This is obviously to show that Loki isn't intimidated or as he says in Avengers "I don't threaten".
I find it hard to believe that Kurse was afraid of releasing Loki.
Does anyone know why he didnt break open his cell?
gpt
Because Kurse isn't an idiot, and recognized that Loki was a gamble he didn't especially need to take.. 

Everyone else he released was a brainless thug, essentially. Kurse wanted mayhem, and the prisoners gave that to him in spades. Loki was collected, smiling, and apparently Asgardian. He was also in a cell all by himself. That sounds exactly like the kind of person who could make an awful lot of trouble, but not necessarily the kind you want. Kurse didn't have time to conduct an exit interview, but probably figured that the potential damage one more rampaging prisoner could do wasn't worth the risk of letting this anomaly free.