Contrary to Spike Lee, I think you can make a genre film with slavery, but QT fails because of the way Stephen fits into the narrative structure. In some ways, I think QT touches on moral issues about genre and movie making more than most, but his cinephiliac focus can occlude moral understanding, too. That Butch segment is, to me, one of the weaker segments in his films once it gets to the hillbillies, but it does get to the contrast you're talking about, I guess: it shows a sense of honor and morality (Butch saving Marcel), while also using cartoonish movie stereotypes (the buttfucking hillbillies). On the other hand, part of the problem I have with it is it doesn't say anything particularly interesting about honor other than what it borrows from some macho movie tropes.
As a moral critic, if he is one, QT's stance can't be separated from movie mediation. Moral questions are always about how morality is reflected in movies.
, wherein much Truth is written.