Rather than respond, Owen slipped the key into the lock. He didn't plan on putting Simms in cuffs. Leaving his hands free meant Simms could attempt to do some damage, which was just fine with Owen. He wasn't worried about Simms getting away from him, and the cuffs were there for a re-arrest. Not that Simms knew that.
Owen slid the cell door back and motioned his arm to gesture Simms out. "We're going to have a great time, don't worry about that. Try not to be too much of a dick, okay?" He wasn't counting on Simms agreeing with him, or being a decent human being, but whatever.