He hears the double meaning to the words and accepts it easily, without pressing; honestly, it's expected. It was more surprising to hear her admit she didn't know something, even when that was the case, instead of going vague and mysterious and acting as though she did. Thranduil had long since learned not to display weaknesses, he would not expect and would not ask her to show hers to him.

"That alone says much of this place's power."

He may not like her, especially given all she can do with such ease given the Ring she wears, but he respects her power. The reputation she bears was not earned falsely, nor lightly.