When i think of a traitor it means someone who purposely switches sides to hurt or kill their current boss. Guys like tessio and carlo were true traitors. In fredos case he was just stupid and naive. Sure he might be a little envious but he loves his family especially mike. In his mind he wasnt trying to take over the family or hurt mike, i think he just wanted show he could help mike like tom and neri do but it backfired. Now some consider him a traitor in order to justify mikes actions of killing him. He clearly had no idea roth would try to kill mike.