[ Kevin's eyes harden, and he looks away. While he understands why he's down there, and Kevin even worked with him, he doesn't like it. He wishes there were an easy answer, that Sam and Dean would just kill him, or let Kevin kill him, but a lot of his bloodlust dissipated after he attacked him with the hammer. Now he mostly just wants Crowley out of his life forever, however he can get that. ]

No. They're keeping him chained up in their dungeon, in case they can get him to be helpful. When they didn't finish the trials, they just never let him go.