In "A Good Man is Hard to Find" by Flannery O'Connor, what would be the "grotesque" element of this story?

The Misfit himself is a grotesque character--a
bloodthirsty, murdering sociopath of the worst kind, who enjoys committing the deed. But
the most grotesque part of the story comes at the end, when The Misfit's partners take
Bailey, his wife and their children into the woods and shoots them, one by one. The
killings are unnecessary, since the family has wrecked their car on a dirt road in a
rural area. The murder of the two children--unlikable though they may be--is a terrible
crime, and allowing the grandmother to hear the shots must have been awful for the
equally unlikable old lady. The final death, that of the grandmother while on her
knees at the hands of The Misfit, comes after she has tried to befriend and forgive
him--another unforgivable act by a monstrous human with an entirely appropriate
name.