In the entire story, the Traveler is never evil. The story has been finished and completed. It's canon that the Traveler is good because of the story. In the Destiny Wiki, it says that the Traveler sparked the Golden Age. It also saved us at the collapse of the Golden Age and sacrificed itself to protect us from darkness. It also says in the Grimoire that the Traveler chose to stay and fight the darkness for us. That it gave everything it had for us. If that doesn't state the Traveler is good, I don't know what else would.