The paper is just listing studies that happened. There might be a political agenda behind it, but identifying a study about cannabis use for PTSD and drawing conclusions about the results is what you would expect this review to do. Leaving studies out is much more suspicious.
How many veterans do you know? How many veterans that you know use cannabis to treat their PTS? I guess I might be living in a bubble but there are plenty of videos of veterans and others talking about how exactly it is that they use cannabis for PTS. I recommend watching some.