A younger Sansa might have blushed at the harsh language or admonished Tyrion to stop. She is no longer that young, innocent girl and she doesn't react to it except to look away for a moment, focusing her gaze on a dripping icicle above her head.
"I will watch while you do so. I think that's impetus enough, my lord."
Re: III
"I will watch while you do so. I think that's impetus enough, my lord."