As more and more LGBT folks come out to family, friends, coworkers, and often everyone else, acceptance grows throughout society. People get to actually know LGBTs in their midst instead of it being a foreign concept. Some stubborn naysayers and bigots will always exist, but it's almost a complete 180 from when I was a kid. Some of this is generational, as younger people learn that just as Santa was a hoax, so were the lies told about LGBTs by older folks. They understand that their openly gay friends are not the monsters they were told they were, and they become much needed allies instead of foes.
Still, gays learn that they can never let their guard down completely. Not unlike other vilified minorities, actually. So the OP's thoughts are relevant even today -- just that the bullying, violence, shunning can still be found occasionally instead of all the time. (Unfortunately, suicide rates and teen homelessness are still issues for younger people just coming out who encounter it.)
So, will your friend find acceptance working for Amtrak? Probably, but not completely. I'd think the on-board jobs would be more gay-friendly than that of the engineer or the yards. I swear I've been on trains where OBS gays were in the majority, in fact. This might translate better to conductor than engineer, but if his heart is set on engineer he should go for it, with eyes wide open. He should try to form friendships with coworkers who will be part of a support system if he does encounter trouble.