"Free Will--I've tried it, I've rejected it"--T. E. Lawrence

From what I've been able to garner from reading about Alvin Plantinga's views, God supposedly doesn't prevent  humans from committing harmful acts because to do so would be an affront to free will.  Does this adequately sum up Plantinga's view?  In any case, the obvious retort that humans prevent other humans from committing harmful acts all the time, with no complaint that free will has been violated--why is it OK for humans to do so, and not God?  When a shark attacks a human, God does not intervene--does God seek to protect the free-will of the shark, who only bites and then realizes that human food isn't to its liking?  I know when a crocodile attacks a human, it's because the crocodile wants to eat the human--but when a shark does, it's a mistake--they don't really want to eat humans.  So why doesn't God at least prevent such mistakes?  Or does God view shark free-will as something that shouldn't be violated either? 

Also, before we consciously do anything, our brain's unconcscious has typically already decided to do it any way.  How is that "Free Will"?   The "Free Will defense" just seems so overwhelmingly inadequate, that I can't see why a serious thinker would use it.  Perhaps others here can provide a more sophisticated rendition of what Plantinga is saying.