The risk for the bug found is not high at all. In fact most of you would never find yourself in the demonstrated scenario. The idea is that if you hand your phone over to a colleague or friend while it is unlocked and take your attention away they can add their own fingerprint with out having to first input your PIN. This is a bit concerning, but the good news is that it is a problem with the Nova Launcher and not with the LG V10. Nova Launcher allows you to add an app activities widget to your homescreen. From there you are able to add the "fingerprint settings" activity to the homescreen, and can then access that to setup your own fingerprint without first inputting the PIN or password. With the new fingerprint added the person could access your phone any time you are not near it. The moral of the story is to stay away from 3rd party launchers like Nova until this bug has been patched.