I ran this at 4-5. And despite being pretty much jackasses the party got a good diplomacy roll that made up for it. Despite hitting almost every neg.
Before I go any further, I want to say in the interest of full disclosure that I enjoy scenarios where there are NPCs that aren't necessarily easy to get along with, but also penalize the PCs if they are unrepentant jerks. That was one of my favorite things about another season 5 scenario.
I also will say, any NPC interaction is dependent on the GM. I tend to recommend any scenario heavy on roleplay not be run cold. The ideal would be to play with a GM who has run it multiple times and has developed some insight into who the character really is. I imagine that isn't something that occurs especially often.
That said, there is stuff in the PCs favor. First, it is more difficult to make Lander hate you. You have to fail the DC by ten or more for his attitude to worsen. Further more, if you just take him out of the trunk, heal him, help clean him up, and feed him, you already have +6 right there. I feel like those would be things natural for heroes to do after rescuing a hostage.
Furthermore, if you can make the DC 20 sense motive check you can find out that if you boast about your own toughness with an Intimidation check, you can use that to increase his attitude instead of Diplomacy.
You can challenge him to a duel. Now the PCs might not think about it, but it also says that Lander will be throwing out challenges himself, and the PCs just need to accept one. If you win and don't rub his face in it, his attitude automatically improves one step, which should at least be enough to get a martial group in the game, even if they don't have a face man.
Also, a PC can take Lander on as a pupil, and as long as he treats him with a little respect, that PC can get a bonus to diplomacy checks.
And of course, there's the ubiquitous, bonus for if you roleplay well.
Of course all of this is optional, only necessary for Pathfinders who desire to "go above and beyond the call of duty." If they want, the PCs can just keep Lander in the trunk, and carry him back.
But at the risk of being repetitive, I think a lot of PCs treat NPCs like brick walls. Treat them however they want, with no expectation of negative consequences. I can appreciate people wanting to play games like that, but I don't think PFS should be a game like that. If your character is just a jerk to NPCs, maybe you should lose a prestige here and there.
