Yes, I think it would be OOC for him to both not agree to it and agree to it right away. It's a tricky area so he's not going to be like her and just think of it as a fun game. But he's not totally against it in the scene we see. He just has to come around to it. His first response is always going to be kneejerk and defensive but if they can figure out a way he'd be up for it, surely.

Plus it's again a great way to advance the way they're both moving this season. She's exploring how she feels about him and sex etc. He's considering figuring out who he is as a whole person instead of separate people.