He's asking her if she wants him to. Well, his whole attitude is different in it.

*nods* The whole thing was sort of reversed, really -- asking Rose if she wanted him to (when he knew it was hypothetical) was gauging her. Joan asking him if he would (when it wasn't) was gauging him. But in both cases it was the woman making the call about whether to continue. Not a one-to-one parallel by any means, but an interesting echo.