The typical person compartmentalizes between a weapon's use in military operations and its engineering. You see similar dynamics with things like military aircraft at air shows. Where kids and adults alike enjoy the demonstrative operation of the machines without ruminating on how many human souls were negatively affected by them.

Compartmentalization is a coping mechanism. That children are exposed to similar military engineering in such a way to make it enjoyable does not negate the nature of a bomb, tank, or machine gun.