It can be taken too far though. If I go shoplifting am I "hacking the shop"? If my shower breaks and I pour bottled water over myself to clean am I "hacking bottled water"?
Perhaps 'trick' would be a better term in this airport case. I guess the difference between a trick and a hack is that you can't trick a machine (it does what it's told and doesn't care what your intentions are) but you can certainly trick people (they can be fooled in to misreading your intentions and responding dynamically). Also a trick is usually just about improving device utility rather than re-purposing it.