Like the mc said, this is a game for ml. He's taking advantage of the mc's lack of control over the situation even when he's, the mc, a cop, a figure of righteousness and authority. But not in the ml's world. He just wants to prove how his, the mc, values can be tainted and his moral manipulated with the 'right' incentive. Also, mc must be emotionally and physically exhausted so his critical thinking is not the best and ml wants to ruin him.
Like you said, breaking the friend's ankle, at least it was only one, was the optimal decision than being gang raped and having both of his ankles cut off. At least he's alive and yes, maybe he could resent the mc because of that but he was a witness of the whole madness, if he survives, and maybe he could forgive him because the cop is full of guilt rn.
He is making everything black and white. The MC shattered the ankle of his friend because he didn’t want his friend to be gang raped and have his limbs cut off. <— that’s a no brainer what to do in that situation - the cop doesn’t become corrupt by smashing his friend ankle. Also it’s not like the friend was an athlete he’s a therapist and a shattered ankle can heal over time - having his legs cut off can’t heal. Also the friend obviously heard the conversation- I’m pretty sure the friend would have welcomed the broken ankle over being ganged raped then having his legs cut off?!??