Jon's expression of deep, profound confusion doesn't let up through basically the entire explanation. He is, in every sense of the word, baffled. All the math checks out, everything sounds convoluted but sensible (even if it's not something he could wrap his head around doing, himself), but he's just so utterly shocked by the whole thing that that's the only face he can make.

"I..." He lets out a mildly-incredulous huff of a laugh. There's so many things he could ask, but quite frankly, the entire thing is so beyond anything he could've expected, he doesn't even know where he could begin with it. "Well, that--- saves you some trouble, then? I guess?"