All things considered, I'd rather think Netero wanted to try everything else before resorting to a nuke. We are talking about nuclear weapons here. It's not like they would be the first choice to deal with anything. The palace was also within a walking distance from the city, if memory serves, so using nukes would have been a bit questionable there, which led to the plan of taking the king elsewhere. Otherwise it actually was a pretty sound plan: He was there alone facing the king to make sure he was the only sacrifice.

I also don't think this was anything so strange in the bigger picture. This arc was about humans vs ants, and inarguably nukes are the pinnacle of human achievements weapons wise. Nukes are also something a single person would have a hard time building, all the way from extracting the needed elements and constructing the facilities and machines to designing and finally building the thing itself. The ants had poured everything into a single entity, the king, thinking it would have everything to conquer the world, but humans never did that, yet proved victorious here.