Lucifer is smart because Istredd is absolutely likely to keep on theorizing and talking out his thoughts, and while he considers himself fairly dry and nonjudgmental at the moment, it can easily be seen as critical of Thorne. He's being critical, that's for certain, and he stops as soon as Lucifer says his name like that.

He understands right away the why and manages to look appropriately sheepish when he realizes how much he'd run his mouth. There are in fact ears everywhere around here, and the Queen is in particular in no mood for critics of her regime.

"You're right, of course. For Thorne."