"I can't assume you'll be able to deduce a fact when, having been ignorant myself of the facts surrounding it, I had no idea that you weren't," he returns imperturbably, shrugging. "I learned several things today. If you already knew them, so be it, but I don't know what you know."
He has a thinking look on. "Does that mean that you'd object to her presence in the lab if she slept elsewhere and stayed out of the kitchen? I think I do know someone here who could use her services, although, as he's a muggle, she couldn't become bound to him. And I do feel a bit responsible; she was very good with the baby snakes who thought no one over four foot five could understand their troubles."
Occlumental spy logic: when it comes to sensitive information, hinting until they get or show they're not the correct recipient is How Communication Happens; saying something outright is Against The Code.