You don’t have to be comprehensive, which I would also suggest is both impossible and not useful. But if we are working out of an established framework, it is always good practice to disclose that. And arguing one view without considering alternatives hardly forms a “case” for anything.

Sure, we can make up scenarios all we want and use deductive reasoning. But if we agree this scenario is not realistic then this sort of makes my point, which is that this stops being “a case for withholding knowledge” that we can use in the real world and becomes “a conversation on reddit about withholding knowledge” for a fake scenario about a sun flare form the future. We can grant the assumptions and discuss the moral implications and it’s all good fun, to be sure. It just doesn’t have real world utility if our deductive process is starting from a place not congruent with the real world. That’s all.