I personally think he really is a fascist, but I still don't think he was deliberately throwing out a Nazi salute. Just naive about waving to a crowd in front of a camera, which is very on-brand for him.
He's naïve about many things but I don't believe any of these people are ignorant of fascist imagery or its trollish power, even if only in some bullshit recycled bad-sci-fi trope sense.
He may be more ignorant than he portrays but he is a malignant narcissist — guys like him don't even think fascism is a bad idea.