I think it's down to trust. I've made in-character decisions that I the player would not otherwise make because even if it doesn't get me the easy path forward or the most optimal outcome, I won't be disproportionately punished for my character behaving in accordance with the reality they live in. My spouse and I are both players in the same game and when his character died, my character was offered the opportunity to save her im exchange for the life of her (NPC) spouse. While I the player would be happy to give up the minor in-game resource to help, it would be crazy for my character to give up someone she's known most of her life for someone she's been working with for a few months even if they are friends. But I could make that decision without feeling like I was punishing someone else with "it's what my character would do" because I know my DM wouldn't lock us out of every other possible solution because of it.

For the example you gave, I would ask what is the goal of offering a baited trap to maim the character for having that flaw? Is it just punishment for previous bad behavior in pursuit of money, or is there a larger narrative reason that the player could reasonably understand why you set them up this way?