Wut?
Kuzan is becoming one of the most interesting characters in terms of writing
After everything he went through, it looks like he wants answers for the things he did, and we already had hints of that since pretimeskip during the Ohara flashbacks even if we don't actually know everything he has in mind.
He is coming up as one of the best written secondary characters easily.
He realized that there are other ways to change stuff around him even without being a Marine.
While Garp thinks the way to change things is joining the Navy, while Garp himself refuses promotions that would make him grow in authority for the Marines, Kuzan realized that doing the same things all over again wouldn't have different results.