Why was "the barn" "every bit as good" in "Wuthering Heights"?

In chapter 13 of Wuthering Heights by Emily Brontë, Isabella is disgusted by Joseph sticking his fingers in the porridge, and takes over the cooking herself:

It was rather a rough mess, I own, when poured into the basins; four had been provided, and a gallon pitcher of new milk was brought from the dairy, which Hareton seized and commenced drinking and spilling from the expansive lip. I expostulated, and desired that he should have his in a mug; affirming that I could not taste the liquid treated so dirtily. The old cynic chose to be vastly offended at this nicety; assuring me, repeatedly, that ‘the barn was every bit as good’ as I, ‘and every bit as wollsome,’ and wondering how I could fashion to be so conceited. Meanwhile, the infant ruffian continued sucking; and glowered up at me defyingly, as he slavered into the jug.

Why "the barn"?

As Hareton is described as an 'infant ruffian', my guess is that bairn (child) is intended. Barn is still the Scandinavian word for child.