That's... a lot more reaction than he was anticipating and the hoarseness and hug take him a little by surprise. Only for a moment, though, and then he's wrapping his arms warmly around Ianto in return, and turning his head to kiss his hair.
"Well, you know, whatever I can do to help you work your way back into kinkier things!" he grins, a little awkward. "It's all to my advantage too, after all!"
Of course it's not just about that - he totally just wants to pleasure Ianto and help him explore and expand his horizons - but, given Spike's attitude to kink, Ianto is also his only option for that kind of fun at the moment. It's natural for him to want to encourage him in it.