Randal admits to being an accessory to multiple child rapes early in the episode, but that is somehow forgotten or just ignored by Daryl and the rest of our heroes. Plots that require our protagonists to be stupid are just sloppy. Plus, if the writers are trying to create some moral ambiguity(as they seemed to be doing with the rest of the episode) why make Randal a villain from the get go?
Because it was never about killing a good man, it was about killing any man in cold blood.
...In my opinion.