"In terms of the level of understanding, not in terms of the methods she's using." He's not going to waste time agonizing over whether or not the supernatural is supposed to happen. It's either true or it isn't, and if magic is verifiable, then it should be approached scientifically. If it can't be, then... it should be...

"Specifically, I'm wondering about your immune system, what's a concern, and what's been taken into consideration."

Then he looks disappointed. Bad timing, huh? His frown tightens, and he nods, without further comment. Damn.