There's no such thing as a bad story idea. There is merely a story idea that wasn't properly executed.
Some story ideas need more execution than others.
A saying I was reminded of, reading TV Tropes. Particularly when reading Jumping Off The Slippery Slope. When a shades-of-gray foe suddenly turns evil so you know what to do, that can be cheating. But that's because the characters act as if the escape hatch eliminates the problem. They never wonder what they would have chosen, while they were agonizing over what to do, if this hadn't happened. I think characters would be more likely to "wonder, till it drives you mad, what would have happened if you had."
Plus, of course, they could have been blamed for not acting in time.
I don't see a way to resolve the story without a similar situation, and the characters do have to chose, but it's a lovely set up.