I wouldn't take the "survey" as much more then opinion. How exactly did they go about collecting the sample size of 6,000+ people? So I'm not even sure its representative of the transgender population to begin with. As I'm assuming that they merely posted an open invitation for people to complete the survey, there are two kinds of people that complete those surveys with the largest group being people who "have an axe to grind". Least of all, people who are happy with their transition are not going to participate in a voluntary survey designed to assess thier perceptions of discrimination. They're simply not interested enough in the topic to participate in the survey.
So if you ask 6,000 people who feel like they were discriminated against if they felt discriminated against, I think the answer is pretty obvious. Also, the notion of self-reported discrimination is pretty vague, its up to the responded to decide whether what they experienced was discrimination (when it might have been a completely different reason they were fired, evicted, etc); futher how do they distinguish from transgender discrimination vs racial discrimination, etc?
If nothing else, the very title "Injustice at every turn..." implies what outcome they were looking for.
"Statistics lie and liars use statistics"