My first thought is that he is neutral but selfish, but in his selfishness he doesn’t mind taking advantage of others suffering to gain for himself, which makes him evil.
But, you have to remember that people who are considered “evil” don’t really consider themselves evil. Sometimes they think they are acting for the greater good. Doctor Octopus thought he was working to solve the worlds energy crisis. Darth Vader/Anakin Skywalker thought that the system of government was in chaos and he had to make everyone listen to his better way. So far, Rumple hasn’t given any indication that his intentions are evil. Regina on the other hand seems to have evil intent.
Rumple is called The Dark One, not The Evil One. Darkness does not imply evilness.
Brian Caruthers
pbandjnetwork.com