Generally speaking, PTSD is an extremely well-documented consequence of killing.
"killing or seriously injuring someone in the line of duty was significantly associated with PTSD symptoms (p< .01) and marginally associated with depression symptoms (p < .06). These results highlight the potential mental health impact of killing or seriously injuring someone in the line of duty."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3974970/
"Killing in War Leaves Veterans with Lasting Psychological Scars, Study Finds"
https://www.ucsf.edu/news/2016/12/405231/killing-war-leaves-...
lots more evidence out there.
And the first of your sources does say that 7-19% of officers get ptsd but also that 25% kill or seriously injured someone, which is a larger number than get ptsd. so that suggests 6-18% officers kill or seriously injure someone and don’t get ptsd. Assuming the ones that get ptsd are the same as the ones doing bodily harm, unrealistic but conservative, that means half of officers who do that could easily be just dandy.
That data was in the intro. The study itself had a drop out rate that surprised me, about half the participants.
Conclusion, better studies needed. Also conclusion, did not support the original point.