Speaking from experience with other manga and the way that rude ass guy was drawn, he either gets killed or is near death when mc saves him and then either accepts him or looks up to him and calls him aniki
Instead of being so roundabout, if he really wanted to refuse (which would end the entire manga instantly because there would be no point then) he could literally reject them harshly once and threaten to work against any of them if they ever approached him again.
I dont think that this problem is as hard as its made out to be. There certainly has to be someone skilled enough in archery, maybe even a couple guys skilled in archery that would be able to instantly kill all of the traitors kidnapping the fmc as soon as the negotioations start. And even if...
How can you be such human scum. I'd be ashamed to write a story containing such people. Their story value is about as negative as temperatures in siberia.
When you listen through the grapevine and hear axe-kun sharpening his tools, you gotta make progress fast
Would be nice if my predictions are wrong though