What makes this argument flawed?

There are a couple of ways to attack this argument, but the main way is articulate this is that the conclusion just doesn't have to be true based on the premises. The conclusion is that Alice should have been charged but nothing in the premises supports this. To prove that something should happen we need a premise saying that under x conditions y should happen, and we have nothing of that sort. The available evidence could also support the idea that bob should not have been charged, that neither should have been charged, both should have, or that moral luck simply plays a role in criminal law.