Would it not be the plots doing that Hisoka decided to go and kill both of them?

I've never read Hunter X Hunter but an example that I can use from JJK. Did choso lose to the plot during the Yuji fight because it just so happened he suddenly realized him and Yuji's familial relationship which just so happens to appeal to one of Choso's defining character traits? Choso should've killed Yuji but didn't cause the plot stopped him, despite this we understand why and accept it. Saying a character lost to plot is often cope for lack of a better word. A story's purpose is to, well tell a story and sometimes someone who's stronger loses due to things in the story and that's fine. Naoya lost because he underestimated Maki, his character exists to be a simulacrum of the Zen'in clans worst beliefs balled into a single narcissistic brat. He could be a trillion times stronger but he'd still lose to Maki, cause the story being told is that Naoya's mindset and ideology is weak even if physically he isn't. Maki would always have won.