If they'd rather cure someone else, or do something else with the cure that a reasonable person could expect to be just as beneficial (and presumably this would still require saving someone's life in some way), then you'd have a moral obligation to help them to mitigate your crimes.

The point is, morally you don't really deserve a choice. The only way you aren't morally obligated to give up the cure is if you are morally obligated to override an obviously immoral choice made by your victims.