for no good reason. You normally don't use the article when talking about professions.
So, out of curiosity, is this word strictly used for the profession of modeling? Or can you also use it as you would in English, like say in reference to modeling clay?
As a native Danish speaker I hear this sentence as the woman being a "model of something" - not model as the profession. Maybe someone is making wedding cake figurines and the woman is still a prototype.