Adrian gains a critical look for the offer, half doubtful and half outright untrusting; in Walter's experience information isn't shared, isn't offered, it's only kept, given when it's required and no more. He's therefore at a loss as to how to respond to such a thing, he can't help but think it's some kind of trick.

"You don't have to, I can figure it out," he blurts out hastily in an attempt to circumvent the whole possibly-a-trick-but-just-as-easily-not problem. It's too quick to really be believed, of course, but it's a matter of pride. More or less.