It's worth noting that in this case we're only talking about keys that are useful to someone in physical possession of a phone. So as long as I retain physical possession of my phone no one can get at it, keys or not.
That's still pretty safe.
The government always leaks keys. Sometimes literally.
http://www.wired.com/2015/09/lockpickers-3-d-print-tsa-lugga...
http://nypost.com/2015/09/20/the-8-key-that-can-open-new-yor...
Plus, any key that the government can use without your permission, they can illegally abuse. And if there's one thing we've seen proven recently, it's that such abuse will occur.