Cannibalism in the Bible?!?

My reading this morning covered 2 Kings 6:29: “So we cooked my son and ate him. The next day I said to her, ‘Give your son so that we may eat him’; but she had hidden her son.”

I have two questions:

1. When there is no law given against something specific (in this example, cannibalism), does that mean that it is automatically permitted?
2. Would Father punish someone by forcing them to sin or is the test for a believer to rather give up our lives in a scenario where we have to choose between sinning or living? There are many examples where people lied to save their or others’ lives.