He definitely has the potential. He's sympathetic to Doorman's faction, which might very well be an enemy of the Activity Club. Forge indicated he was going to join said faction, and Spender's reaction implies he knows about said faction, but he had no issues with killing forge anyways. So if Isaac gets fed up with the activity club, he may end up throwing in with them; making him a pseudo-badguy. Especially if the storm spirit is as powerful as some people are guessing.