So what you're saying is if I watched somebody put their password into their computer, and did the same to login to their system, that's 'hacking'. If my friend didn't let me use their Internet connection, and I hooked up using Ethernet, that's 'hacking'. If I mugged an old lady for her car keys and drove off in her 2CV, that's 'hacking' (after all, I am getting access without their authorisation).
The only reason I believe we're having this argument about this is because touch sensors haven't really been used in the general public, with such integration. Look at it from the bigger picture and you'll see that cloning a fingerprint is not hacking. There's really no difference between that and learning somebody's password -- both are a code that will need to be entered identically.
Going off of the definition I cited, I don't believe it's incorrect to say it was hacked. As far as your example of the car keys, hacking is generally a term reserved for computer systems. Learning someone's code and gaining access could be considered hacking if the whole point of the security layer is to prevent unauthorized users from gaining access. Someone being able to "steal" someone else's password and subsequently gain access is a weakness of the system.