S did not force himself on M. Objectively, he abused his power to make a trade for personal gain, and that's what you're judging. M was in no way forced to do anything and the way the story is presented is nearly as guilty as S in that she abused her sexual power for gain (undermining justice in the process) to free someone. The way it is presented, we don't know if it's altruistic or selfish.

For reference, I was JMSR.