First of all, you weren't complaining about what they said (or wrote, but whatever). You were complaining about the motives you imputed to their choice to say that thing. I mean, fair enough. I don't agree with you that it was principally virtue-signalling, but it might well have had an aspect of such. In general, I tend to assume that nearly all journalism, at least that where the journalist selects the topic and the tone, is largely virtue-signalling.

With respect to the factuality of the author's claim, I do entirely agree with you that women are more trusted than men, whether indigent or not, in the sense of "trust" that means "we'll let her stay at our house", and also likelier to be lent aid. They are not, I think, as likely to be believed, which is a sense of "trust", but probably not what the author meant. Mind you, I think the author is correct that a white person is more trusted (in both senses) than an immigrant or a non-white person, especially in America, especially in the American South. Then again, what do I know.

You say that you expected the comment to go over badly with "the average HN commenter". Of course, there is no "average HN commenter", but anyway, so what? Virtue-signalling that appeals to the mean (uniformly-weighted) opinion of society is low-value and ineffective, both game-theoretically and in practice. (Because it is cheap to do, most people do it at a general background level, thus it is a weak signal, and thus only children try very hard at it. But some consider it rude to allocate zero effort to it. Shrug.) Effective virtue-signalling, such as perhaps yours, is that which demonstrates one's bona fides to an in-group by visibly sacrificing something else. A typical sacrifice includes some reputational standing with another group. Game-theoretically, and practically, that's a much more convincing virtue signal.

But you say you didn't intend to signal your virtue. What, then, was the purpose of your top-level comment? I mean, just as you question the author's motives, it seems natural to wonder about yours. When you did it, it seemed like a hijack of the topic, to complain about a minutia of the article. Not very useful, you know? I know this mostly speaks to my lack of imagination, but I just can't see a reason to say what you said, other than to position yourself as being in opposition to the author's foolishness. And worse than foolishness, the author's not just wrong, they're "virtue-signalling", which is to say they're conducting themselves in a way that appears to be about something other than reputation, in order to gain repuation! Attention, do not let this work on you! Actually, that seems like a high-probability explanation of your behaviour, but only a medium-probability explanation of the author's behaviour. (Alternate high-probability explanation of the author's behaviour: the author is just a trite writer, fond of copying others' ideas.)

Anyway, the point of this whole comment is to ask "WHY are you complaining?" So, to answer your question about "how would you go about pointing out X without virtue-signalling"... often the answer is "you don't point it out".

And yes, let me save you a little trouble: like your commenting behaviour, surely virtue-signalling is a factor in my commenting behaviour. At some point after you are introduced to the idea of virtue-signalling, you get around to noticing that most (public) behaviour has some aspect of it. So it's mostly not worth bringing up, as in this case. All in all, personally I think your comment would have been much better if you'd left off the first sentence and the word "ironically". Especially if your goal was not virtue-signalling.

That reminds me: Could you help me to understand what sense of "ironic" you were using when you said that it's "ironic" that "support for homeless/transient women is vastly superior to that available for men"?