The Cyborg Superman returned to Earth after the Manhunters revived him, right during the later moments of Blackest Night (Xanshi was in orbit, Nekron was there). He saw his wife and fellow crew members alive as Black Lanterns, but they did not see him. His presence was totally ignored.
He actually attacked Nekron, but even Nekron ignored him.
For the Cyborg Superman had no heart, and thus nothing that the Black Lantern’s could feed on.
Tags: Adrian Syaf, Blackest Night, Cyborg Superman, Green Lantern (Hal Jordan), Green Lantern Corps, Spoiler Warnings, Tony Bedard