I'm not the one that made this post but it would track with the general reddit-like nature of their other comments. It sounds like a very common thing I hear from reactionaries IRL that are clearly made-up or are hyperfixating on a hypothetical or outlier incident instead of just understanding that is not a failure of trains. Like the whole context was "sometimes trains aren't good actually because I saw a mentally unwell person I have no proof is actually homeless." Not all unhoused people look like the caricature most people have in their head, and not everyone that does drugs in public on a train is actually unhoused, though the latter is certainly a more reasonable assumption to make. The combinations of all these characteristics of this person it was clear they were engaging in bad faith at best, and outright lying at worst. I am not making a judgement either way but it is a specific sort of reactionary thinking that is encountered all too often in online communist spaces, and so it's no surprise when people have short patience with this sort of thing.
If you've seen it enough you tend to get a sense for this time of debatebro and it's rare that it's a simple well-meaning misunderstanding because if it were it is very easy to have some humility. It's the getting all offended by people laughing at something that is a textbook reactionary response, in a place where bullying libs and reactionaries is a pillar of its community culture. Furthermore going around other instances and complaining about said community sort of makes you fair game and I would not call it brigading, especially in a "what are instances you hate" thread, wherein the User compared us to right wingers. Which is itself a very tired very old trope known as "horseshoe theory". And last but not least there is the term Tankie which is most often used to imply people on the imperial periphery or global south seeking national liberation are following a problematic ideology (because often the word gets used to refer to anyone left of Bernie Sanders on foreign policy a "tankie), which has deeply white supremacist or western chauvinist connotations.
So in short, does it really matter whether they live in LA or not? They certainly have a colonizer's mindset with regard to their local community even if they claim to be for "paying for more social services." That is like the core reason why social democracy and liberalism are derided as fascism lite by most communists.