Toby let himself believe that the excitement in the kiss was just as much for him, as Chris' plan. That was why he was doing this. To see the man happy, and maybe have a bit of that directed back at him. It was selfish, sure, but considering all he had here was his life, his daughter, and Chris (although, arguably, Chris controlled all three of those things more than he'd like to admit)... well, it was the only option, as far as his priorities went.
He nodded along with the rest of the plan, actually smiling along with Chris' laugh, before pressing into him again, kissing his neck.