You don't need an abnormally high intelligence to be a train engineer. You need to be alert, methodical and disciplined. Psychological stability counts for more than intelligence. How do gays rate on that scale?
IQ does correlate with passing professional tests.
But I’d posit that gays are positively correlated with obsessive behavior and precision in completing tasks—which would correlate with your description.
My point was simply to debunk the idea that gays would need AA to become train engineers.