[if he just looks perplexed for a moment, well...maybe it's still just a bit strange to him that humans are oftentimes so against helping others if they don't get anything in return.]

You do not have to fight. No one will force you to, and you may live as peacefully as is possible here in the meantime if that is what you would like, with all the necessities for living paid for by Shibusen. But there really is no way to be sent home any sooner besides bringing the war to an end. You could wait around and hope that BREW decides to return you, but the only active role one can play in returning is to fight.