An airbrush does not know or care what it's pointed at.
Airbrushes (in general) can be used for models, fingernail art, make-up application, cake decorating, T-Shirts, auto body art, illustration work, computer case art, phone shell art etc etc. The applications are endless, only limited by your imagination and individual skills.
As long as it delivers the spray pattern you desire while using a suitable medium, you can use it for anything.