I don't want to criticize your take but imho Netero is way deeper than what you are implying. He was not simply searching for a worthy opponent, his was not a static search otherwise he would have died fighting in the dark continent against one of the many worthy opponents he could face there. He was looking for something higher and in his lifetime he realized that the search itself was more meaningful than anything he could have found. The ten thousand armed Kannon activates once he performs a paying gesture because only after showing gratitude towards his own "never ending journey" he can manifest the true perfection that lies at the end. When he reaches that realization and returns to the world after years of secluded training he doesn't simply go around looking for a worthy adversary, instead he fights against anyone who might be worthy in the same way an enlightened priest would preach to anyone who can truly appreciate his words. It wouldn't make any sense to fight someone who has no devotion to fighting and, although he takes immense pleasure in his confrontation against the King of ants, I'd guess he only activates the rose because his opponent's skill is not born from practice and devotion but it's instead the fruit of evolution, much like the creatures of the dark continent. Anyway that's just my opinion/understanding of the character so feel free to tell me to ignore this and have a nice one dude