The nuke was the entire point of the arc.
Notice how high the power levels were in that arc, the point was that the chimera ants were never a real threat from the very beginning.
Meruem talking about how superior his species was, Netero talking about the human malicious evolution and using a weapon that wasn't made to kill the ants, but to kill other humans.
The HxH world is basically our world plus some fantasy shit. They have cars, videogames, weapons, computers, internet, smartphones etc. East Gorteau was literally North Korea.