I'm not saying it can't or shouldn't be discussed, but the author was so conscious of the correlations made in the article that they felt the need to literally write that they're not trying to make those correlations.
There's no shortage of people linking transgendered people and mental illness, just as there's no shortage of people linking homosexuality to mental illness. If you're not trying to strengthen those assumptions, then use different examples... it seems lazy to just try to hand-wave it away in a sentence rather than using a different example.