Gale can be super sleezy, I'll grant you that, but I don't get the impression he'd commit mass murder to gain power, which seemed to be implied earlier in the thread. He'll just passively endanger the lives of everyone around him rather than isolating himself in some safe place. A pretty solidly true neutral character, I think.
Is he a psychotic mass murderer? No, not until the bomb goes off at least. But he is either an idiot or the more likely an extreme narcissist. You don't go around messing with cosmic power unless you've got a serious ego or severe inability to comprehend the kind of damage you could cause. Becoming a walking bomb capable of leveling a city is not something a neutral or good person does, at least I wouldn't think they would. At least Wyll only screwed his own soul, Gale's on a whole other level of "fuck the consequences".