That seems like a very good idea, taking his keys to ensure his safety!

I have read in various places (including one of my past psychology class textbooks) that the brain has an incredible ability to heal from various injuries. That some parts of the brain that normally don't handle certain operations can learn to (in a sense). If my recollection is correct, then I could definitely see Steve's cognitive issues possibly improving notably. I know that some forms of dementia do have bleak outcomes, but maybe Steve will, indeed, heal from this ordeal. Of course I don't know the complete nature of his brain injury, nor would I fully understand it, if I did. But I am quite hopeful for him.