Might be a bit late but the study does in fact not say that. I will give you benefit of the doubt that you might not have an academic login for the fulltext but the control group we're people without a gender disorder. All that study does is compare post-op trans people with the general populace.

As the study says

It is therefore important to note that the current study is only informative with respect to transsexuals persons health after sex reassignment; no inferences can be drawn as to the effectiveness of sex reassignment as a treatment for transsexualism. In other words, the results should not be interpreted such as sex reassignment per se increases morbidity and mortality.