I think this is why we glimpse Captain Wentworth sneering at Mary when she's being a snob and rolling his eyes at Mrs Musgrove when she's grieving her useless son. We see his humanity. His is a "frank...open-hearted..eager character" who's sincerity she can depend on because he "sometimes looked or said a careless or hasty thing"

Is Austen fatphobic? Earlier in this paragraph she mentions that fat people are more fit for "good cheer and good humour", the stereotype of the happy fat person still exists today. But in the following paragraph Austen seems to apologise saying everyone, whatever their size, has a right to be emotional and it's a distasteful to ridicule emotional people for their size

She would have waited till he had sufficient money to marry - a long engagement like Mrs Musgrove abominates in Chapter 23