It seems, if I am not mistaken, that I may have caused some offense. If so, I apologize, and I sympathize with you if you're in a situation where "queer" is an insult - my intended meaning was that: "straight people shouldn't, in general, say "queer"... with rather few exceptions" isn't the case everywhere. In fact, I'd expect that if one were to try to use "queer" as an insult around Cambridge, one would at least initially have difficulty conveying the intended meaning. We've even got queer straight people.

May I take a guess as to the social groups I suspect you've encountered this in?

Of course! I'd guess that a good first approximation of these social groups is the demographics of a good American college near a prominent body of water (for some reason, this seems to correlate with social liberalism). The only caveat beyond the implied racial re-calibration is that my social groups tend to be predominantly female. And certainly my experience would be different in other settings - as I noted in the grandparent.

But I really think that there's a huge difference between white supporters of racial equality and non-queer "allies" WRT their relationships with the respective groups in question.

I would be very curious for you to expound upon this.

Well, that's a whole complicated issue, but the big thing that jumped to mind was that the "supporter" group in "alternative-sexuality" politics is often lumped in with the people they're "supporting" (gay-straight alliances, the addition of "allies" to the ever-expanding LGBTBBQ acronym...).