Because there's not necessarily a causal relationship here, it's not like you suggest. They wanted to show his deeds entirely and so yonko clashes were mentioned. It doesn't implicate it was them to capture him.
Bro you don't know why its stated. You haven't seen his flashback. They could always hurt him. Once again you thought Youkous couldn't hurt Kaidi when his introduction showed a big ass scar on him. Hurting n killing two different things
and he wouldn't be captured if he was on Rocks it took place after god valley
What's going on here, are people actually debating if capture and kill mean the same thing?