Being harvested is a risk of going down in this city. It does not need your agreement in advance, any more than being robbed does — if you bleed out somewhere with the wrong people standing over you, what happens next is part of the story. Do not open a report because you woke up short a kidney.
What the surgery is not is a licence for anything else. Torture, sexual content, or gore aimed at making a real person uncomfortable falls under 2.5, and anyone who says out of character that they want out of that gets out, immediately and without argument — the harvest can still happen, the scene around it stops.
And it has to be a scene. Selling a kidney because your character is desperate is a story; standing at a hospital door taking organs off everyone who drops is farming, and will be treated as it.