Chouji is unwilling to sabotage the Iron Eye's plan either through the bomb or those building it. The bomb, he feels they don't understand nearly well enough to make the hazards worthwhile. He thinks that they're just as likely to make things worse in the attempt. Then we come to the people responsible for making it. First of all, even killing them would stall the plan for a very short amount of time, given the way revival works here. That's not something he's used to figuring into things. Harming them or telling the Malnosso would entail turning on Bil, who Chouji's teammate risked his life protecting and who Chouji has been informed has frequently acted in ways that benefit Luceti.

He doesn't think they could get away with pretending to be uninvolved, either. Doing nothing is a tempting option, especially when it means someone else takes care of people they would otherwise be forced to fight, with no outright risk to them. But if they're accepting that it happens and he assumes they'll take a portion of the blame anyway, Chouji would rather try to get a new ally in the process.

And that is important, at least according to those he trusts. Chouji knows he's a new arrival here in the greater scheme of things , so when it comes to politics, he's still relying on the opinions of his friends. Many of those opinions have been that Luceti needs allies outside of their enclosure.

None of the options open to the volunteers on the mission seem ideal, and Chouji can't say he has no hesitations about choosing this one. He's listened uneasily to the idea of escalating, of the Third Party changing tactics and using a weapon like this against them. Then there's the way they'd killing people. It's one thing to do so in battle, with his own hands. He's never participated in engaging a weapon of mass destruction, nor is he usually the decision-maker or strategist. He can't say he likes it.

In the end, Chouji is choosing the option that keeps these people from ever attacking his friends and comrades.