Cheaptrick–your enthusiasm for learning and using languages is amazing, truly. I hope you never lose that.
But--you, yourself, pointed out that the manga isn't going to use complicated language, as it's a shonen manga. Does it even seem the least bit logical that it would use a comon, everyday idiomatic expression in a literal sense if that's the case?
I'm going to be very rude and offer some unsolicited advice. Feel free to ignore it if you so choose. It is, after all, only worth exactly what you paid for it, lol.
Every language has instances where if you stare at a sentence long enough, you can come up with alternative readings--For example, in English this is particularly true when there are a lot of subordinate clauses, because it gets confusing who/what is doing the acting and who/what is being acted upon. Context, then, is what holds the key. The context here, as Aohige has explained several times, makes the sentence make more sense if it's Kuma who knows where they are sent. My dh says the same. It's exactly as Greg says--when asked, they will stare at the page with their heads cocked to one side, then say "Well... Yes, it could read that way, maybe… Under certain circumstances." They just forget to add the part about it being unlikely in this case, because to them it's obvious, and they don't want to be rude. (Oi, I don't want to tell you the conversations we have over this exact sort of thing, lol) Languages don't exist in a vacuum--the words of any given language have meaning because a group of people all agree on that meaning--otherwise communiciation would be impossible, right? That's how usage and meanings change over time and new words are added, while old ones are discarded. So, when the native speakers of a language are not themselves thinking it's ambigious, then by defintion, it isn't.
I understand you may be feeling up against a wall due to all the abuse being heaped upon you, and needing to save face, but maybe withdrawing from the field is the better part of valor in this argument. This is just a silly internet forum after all, and while this may dog you for a bit, after a while some new person will make a mistake and everyone will pile on and try to feel superior over them, and your faux pas will be forgotten for the most part, only to be raised here and there as a joke. Truth be told, the more you struggle, the longer that process will take, and the more ridiculous you seem (no matter the reality).
So, be kind to yourself and let it go. The simple fact of the matter is you made a mistake. Big deal. Everyone makes mistakes--it is often how we learn. However--FTR It is insulting to a native speaker to tell them to look something up that is so very common and every day, especially when they have said the meaning is clear as day to them–especially if they are well educated, as Aohige is. My advice, about as useful as the rest of this post, probably, is to simply man up and apologize for that.
So... What do you all think Rayleigh's offer in this chapter might be? Given his potential involvement and crazy strength, it could be almost anything. Darned if I can think of anything from existing text--and Oda does like to foreshadow. But perhaps everything is up for grabs--perhaps there is no narrator box, perhaps, as Greg suggested, Chopper is reading a paper about something that happens after that offer.. What could it be? The possibilities are endless--or are perhaps related to the unprecedented attack on two Celestial Dragons perpetrated by the SH's, as Robby suggested. WHat do you all think?