significant exposure to violence and studies suggest trauma, drug abuse, and mental illness at rates far above the general population. One study in Australia found PTSD prevalence among street workers above levels of war veterans.
I think that study you linked does more to prove there isn't significant risk of increased PTSD for prostitutes. It's very close to the general population average. Since it's an average I would think you could find other professionals with more PTSD likelihood, such as trauma surgeons, social workers, or social media content censors.