Alright, my previous comment was too fuzzy, let me try to be more clear.
Directly contrasting a specific "non-white marginalized group" with "all white people" does, for me, evoke the impression as if the assumption was that there were no people among "white people" that could be marginalized the same way.
> He only said that that serial killer targets black runaways, and that that is a marginalized group.
This is the part of the comment I was replying to that I took issue with and felt I had to rebut, because it's simply a false summary. The original comment definitely was a stronger statement than that through the broad comparison it drew.
If the original post had been phrased "... rather than white middle class people" (which I believe was the intention), I would completely agree with it.
That strongly implies that a white person couldn't be marginalized.