"An anti-villain is a person that does crimes/villainous deeds for what they see as a noble cause. An anti-villain is the opposite of an anti-hero, but an individual can be both depending on their goals and how they are willing to obtain them."
The Red Lanterns see what they do as a holy crusade, even "the Judge" decided that she could not see Atrocitus as guilty. Although his goal is the death of the "Guardians" and their creation (green lanterns) he, along with his Lanterns go around "punishing" the guilty, they do NOT kill innocents unless they really have to. When he arrived on Earth the first thing he did was save a bunch of people in a train from criminals, even Carol said that "love" was protected. He then went on to burn a bunch of prisoners because he could feel the rage of their victims. Like I said before, if Marvel's Punisher is not considered a villain, neither should Atros.
With Black Adam and Sinestro I understand, they have done some pretty questionable stuff but at least Sinestro think he is doing it for the greater good, as selfish and ambitious as he is. Even though his methods may be seen as "evil", he actually cares about his people.