Frankly, I think you are making a big deal out of not very much. Unless you have proof that the airline employee "willingly and knowingly" gave your passport to someone with ulterior motives, all that you can say is a (probably honest) mistake was made. Who was this other person? And why would you expect identity theft. Unless you have never travelled, or never used your passport as identification anywhere, or your passport is brand new, your passport details are already 'out there'.