The Doctor stood in the corner, with his arms crossed over his chest and a good sized scowl on his face.
The way Cas was explaining things was not at all how he'd say it, and it was outright bothering him. He was not stating things correctly. But as the adage went, if you wanted something done right...
"I don't agree with how he explained it," the Doctor said, standing up off the wall to his full lanky height. "And some of what he said is factually inaccurate. But then," he continued, smiling very slightly, "he's not a doctor. There are far more than four necessary muscles in the thigh. It's just the four with the wrong attachments and origins. And it's not 'our' physiology that's wrong, unless we've slipped into some kind of alternate time stream or dimension. Trust me. I've been around."
"I also don't necessarily agree that they're dangerous, aside from the simple fact that there are a great many of them and so few of us. What he said is right in part-- someone or something put them together and left them. I've seen no evidence to suggest that these people know they're any different from us, or really, that they've got any idea what's going on here."
He sighed, not liking what he was going to have to say next.
"There's something else I want to get out of the way," the Doctor said. "You saw me arrive. That blue box outside, it's what most of you lot call a space ship. I'm not human. But the important thing you need to know about that bit is that whatever's running this place, whatever brought us here... it disabled part of my ship. And that takes an intelligence that very few beings have."