Whenever I see "there is a planet in the habitable zone, but it's a gas giant" I always think gas giants can have rocky moons so it's still a viable candidate for habitability.
Finding a gas giant isn't a downer. I would even go so far as to say a large gas giant in the habitable zone potentially increases the possibilities of a habitable world. Even accounting for radiation belts. The number of moons they can have ups the dice rolls.
