Jack can't help staring a bit, both at the depth of the revelation and at the nature of it. The thing is, he doesn't really get how much effect he has on people. Or at least, he's aware of it in as much as it gets him what he wants, but he really doesn't get how deep it goes, especially with someone as sensitive as Reid.
And as for Reid and Kitty, he came in on that once it was already a thing, and so in many ways it was just how things were and he never really thought about why. They just always seemed really meant for each other, until suddenly they weren't.
"What? More sense? How would we make more sense? And threatened? Seriously?"