Unchained Demons have this weird thing where their quantum furnace of being, which is their version of what you'd call a "soul", is completely separate from their body. It's why they're perfect liars, and their feelings are unreadable unless they actually want to show them. I'm not sure how such an ability would work with them, since what I just said doesn't quite make them immune to things like mind-reading (though they can still resist supernatural effects).
The choking point comes from the fact that Unchained, while in Cover, have the ability to automatically "spoof" any effect that would reveal them as anything other than human, even if it doesn't target them directly. Also relies on the integrity of Cover though.