Kylo's assessment is entirely correct. Though Ronan is highly selective in choosing his master, he's liberated by his surrender. When someone knows exactly what they want from him - exactly what they want to do with him - and makes that intention known, then his otherwise perpetual inner conflict is resolved.

This is what it means to be a dream.

And at the moment, he's an obscene one, perfectly attuned to Kylo's fantasy and elated by his part in it. A breathy moan escapes him as his hips quiver in answer to Kylo's probing tongue, begging for more - as much as he's able, while Kylo's grip on him remains so firm.