This back-and-forth with Nishi's personality is getting tiring, and Kurono made no effort to explain his position. He should've explained WHY he wanted another way. As far as Nishi knows, the aliens fully intends to wipe humans out, and he is trying to wipe out the aliens before them.
"What's your deal?"
"Oh, let's find another way, but I won't tell you why we need one in the first place"
*punch each other
"What's your deal?"
"What's your deal?"
At this point, I am only reading to find out who the German otaku was. He doesn't seem connected to the invading alien race, and the words he used were similar to Nurari.