I read back over the post I made earlier, and had a fresh sense of how easy it is to say something thoughtless about people who actually exist. This is one of those things that I've slipped into a little too easily in the past, and now it seems I've slipped into it again by letting my cynicism about things eat into the rest of my behavior. It's too easy to talk about stuff you know at second- or third-hand as if you own it.
It's even more depressingly easy to impugn motives, or to ascribe them to behavior that is not in evidence. It's even easier than that to do it to someone who isn't in the room, and who you have some reason to believe will never be in the room, because they seem to be way on the other side of things. And yes, it's still possible to believe in such things in the here-and-now, up to the moment you find the person you've impugned is now speaking straight to you.
There wasn't much I could do except apologize as directly as I could, annotate the post, and, well, feel foolish. Nobody likes the taste of their own foot. But here we are.