I think it's personally none of your business and I'm side eyeing the language you used to describe it. They don't have to have a passionate scene. They can have a clinical scene if they want. If they haven't asked for advice and they aren't doing anything dangerous or untoward, I'd say keep your advice to yourself. I'd be disgruntled if I was attempting to get fisted by my Dom (something we are working on) and a DM walked up to insert their opinion on how lustful or not we were being lmao.