It’s an adverisement and the boy is presumably an actor, who knows if the gun is real or a prop. It’s s ridiculously stupid ad to be sure (and a ridiculously stupid sounding candidate) but let’s still distinguish real life gun safety principles from TV.
Most people understand when watching something scripted (like an ad or a movie) that we don’t have to be range safety officer the entire time. Hopefully you’re not the kind of person that goes into a theater shouting out “OMG The Hulk is pointing the Ultimate Nullifier at Galactus and his finger is on the trigger!”
Object to the stupid candidate and his stupid positions, not pendantic arguments about gun safety.
1) In a sane world, elected officials are meant to be responsible people in elevated positions in the community. Therefore they should act in a responsible manner and one that the community should look up to because of their increased visibility to the public. I don't know about you, but posing with one's gun collection while jokily intimidating and threatening to shooting a minor for offending one's daughter is anything but being mature, responsible or holding one's self to a higher standard of behaviour than the average person, not to mention that he's exhibiting such behaviour in front of a minor, and also it conforms to known stereotypes. It reinforces toxic behaviour.
2) Plenty of people take their cues from the media they consume. I don't think it's a stretch of the imagination to say that most people do to at least some extent, but logically the closer the representation is to reality (in this case, Kemp is actually a politician who is campaigning for an actual position), the more likely it is that their behaviour will rub off on viewers.
3) In your example, it seems logical that the Hulk would actually be firing at his target rather than pointing a gun at them with any intent other than to fire in that direction. I'll give a better example: A cop show that regularly depicts the police as 'the good guys' yet they're pointing firearms at people to intimidate them (and/or as part of a joke) with no visible negative consequences.
To integrate all three points: A person who aspires to be in a position of responsibility and elevated status in a community, whose behaviour is more likely to rub off on members of his community, is doing something stupid and unsafe with a firearm. The most likely people to take this behaviour onboard are the ones who aren't the sharpest tools in the box. Logical possible outcome: Firearms demonstration / joke goes horribly wrong.