Kyouya let it happen - he always let it happen, even if most of the time, he didn't care - with the same sort of calm he'd had the whole time, eyes not leaving Nata even as the-- thing opened up. "Interesting." It was, it was very interesting; he was actually somewhat curious about the whole thing, even if he was relatively positive it was an illusion. So was Nata learning from Mukuro? Was that his purpose?
It made sense. And the whole thing was convincing; Hibari's second tonfa snapped out, ever ready to go on the offense, and then he took his first look upward.
"... You're going to make a mess," and a look back down, brief annoyance at the other's weakness - kids didn't cry that easily, did they? - but otherwise no actions taken. This was actually something he could wait for (and kicking little herbivores while they were down would not be enjoyable if it cut off whatever was happening). He was positive he could defend himself, anyway.