I think you're taking "underground railroad" a little bit literally. The commenter seems to be claiming they work in politics and that their job has recently involved putting together some materials to work around some newly introduced (or proposed) spiteful laws targeting a specific group of the population.

I mean on the internet anyone can anonymously claim they're anything, but what this person in particular is claiming doesn't sound out of the realm of possibilities at all.

Indeed, I think the poster was referring to a metaphorical railroad. The term comes from https://en.wikipedia.org/wiki/Underground_Railroad