Why is Dembe's name on the Blacklist?

It's an ever changing list. Red has certain enemies that are on the Blacklist that don't pose an immediate threat to Red's criminal empire. He will get to those when he has "free" time. He often puts new names on the Blacklist that pose an immediate threat. That episode Red thought Dembe had betrayed him and tried to kill him so naturally Dembe's Name was put on the blacklist. At the end his name was taken off. Similarly Mr. Kaplan's name would not have been on the list but was put on after she became a threat to him. I'm sure Agent Gale will be a member of the Blacklist eventually if not already. We will find out in season 5. I really hope this show is not close to ending. I have heard rumors that season 5 would be the final season but I really hope if is not. It started out slow this season but by the end was as good as ever.