There's no reason for Sam to doubt this — it fits the tone Dean had provided — but he struggles with allowing himself the relief of it. The part of him that feels responsible for the dearth of support in his absence, the part that believe no one can know Dean as well as his brother, doesn't allow for it. He shouldn't be threatened and doesn't have any right to be defensive, and yet he feels very much that way, particularly in the face of Geralt's nonchalance.

"Good." If he's relenting, there isn't a lot of heart in it, but some. He nods to himself. "That's what I wanted to hear," he tells Geralt, mostly with his eyebrows.

A moment later, he's back on his feet and carefully pushing in his chair. Fingers tapping against back, he seems to consider saying something else but eventually nods a second time and then dismisses himself without another word. He doubts Geralt will complain.