I've been trying to go through and see if there are any other allusions that would make it a political statement, but can't really find anything. Maybe that ants were chosen as the enemies who inhabited the island? but the "moral" of that arc was "hell yeah kill everything, even the kids" so I really hope that wasn't meant as an allusion. It's not like the manga makes any political statements in general, it's your typical generic shonen "helping people is good" and "get strong" kinda themes. I guess there's a bit talking about people trying to forget Jeju Island, but it's played entirely in-universe. Seems too strange to be coincidence though.