And as Nazrin has seen time and time again, backing down hasn't gotten her anything, either. I mean, I agree with you fully on the logic of the situation, but it largely ignores what Nazrin has been through. It's pretty clear we're not going to win and we're not going to get anywhere, so let's take some thumbs and at least get that much. We've done pretty much nothing but let other people trample on us lately and have gotten squat for it. So let's trample back. At the very least it'll get us a good eulogy from Yuugi, which is a damn sight more than we've gotten anyplace else thus far. If she has information to give, she can gasp it out while begging us to put the knife away.
Edit: Not that I'm opposed to other ideas, but I would think it would have to be something great, given Nazrin is pretty much a prisoner at this point is is being actively prevented from not only advancing the job, but also quitting it entirely. Given literally the only people who have really shown any desire to help are those who are completely unable to help, and that anyone in a position to help has either refused, tried to exploit us, or just not wanted to, Why would Nazrin not want to smash this little wannabe pirate's face in at this point? She's got pretty demonstrably nothing to lose.
Edit edit: In fact, let's take this logic a bit further, because Nazrin would. She has gotten literally no respect from anyone who doesn't know her previously, with one exception. She got none from Cirno. She got none from the farmer whose crop and wagon she saved. She got none from the busybody council member who went on to give Ichirin the third degree behind our back. She got no respect from our own home villagers, who tried to gyp her for saving their lives. She got no respect from the one shyster herbalist who tried to take her money for pisswater. She got no respect from the owner of the wild rose, who did gyp her and terrorized her new friend, and has the gonads to try and report Nazrin for calling her out on it. She got no respect from the archaeology team whose work she took time to advance by showing them the find of the century. And now she gets no respect from Murasa when she tried to help her no money down, and additionally gets no respect from this little buccanette. Did I miss anyone?
She's gotten respect from exactly one person who didn't already know her or she wasn't buying something from. Yuugi. Why did Yuugi respect her? Because she demonstrated that she are not to be messed with. She have not demonstrated this to anyone else, and she has been burned every single time. People on this continent believe Nazrin is a pushover. This is why she is going to have a hard time not beating the shit out of this human anchor and dangling her off the boat, and has every reason to do it. Screw this boat and screw Murasa, she'll get another one.
Edit^3: Okay, forgot about Momoka and Ellen. So we have two people who are grateful we helped them.