The problem is acting like definitions are fluid when we're not. If I write a huge paragraph about how black people are violent, but mention in one sentence that I'm talking about black people as a symbol for power and not as a race, that doesn't change the fact that I just talked about an entire race as a whole. It's still ignorant, and blurring the line between race and culture is a dangerous rabbit hole.
Definitions are pretty fluid and the top level poster did take time to try to qualify the definition for the purposes of discussion. The problem is that fully qualify a definition often results in a long essay that nobody wants or has time to read, and trying to come up with a new label that's both accurate and accessible to the casual reader is a very slow and difficult process.
Since HN is a well-educated community, on the whole, it's not unreasonable to expect a little more work on the part of potential readers than for the same comment posted on a broader platform like Facebook. Unless I know from prior experience where a particular poster stands, when I read a comment I find attitudinally startling on HN I try out a few different interpretations before making assumptions about what was meant.
Personally, I agree that unclear or shifting definitions are bad for discourse.
And in this case, I would agree that there are better ways to express the idea.
I used a stronger tone than necessary about your original reading, I didn't mean to be hostile. But I did think it was clear that the poster was not generalizing as broadly as you took it.
