Well thing is, any other group of fighters would have all instantly died. The king casually strolled by Netero and grandpa Zoldeyck, he's probably faster than anyone without specific speed-based powers and even then, those were hundreds of thousands of punches flying the king is probably faster than specialists still.
The reason they didn't just drop a bomb I suppose was because if they messed up once doing it by automation (dropping from the sky) then they may lose their chance if the ants survived and learned about wmd's. They probably wanted someone skilled enough to ensure the bomb would hit home.