I don't object to it; I just don't recognize it in me.
I don't see being "nice" as being incompatible with being middle class, or any class. Niceness is a universally recognized quality. The point I'm making is that the social circle I have formed as it did because of that, and not because of what school I went to, or my profession, or where I live, or the multitude of other things which determine the class of a person. The survey asked what sort of people are in your circle, and I put pretty much all of them as it's true. My contention is that's less to do with class than with personal qualities and happenstance.
The survey, as you point out, doesn't ask about education or upbringing, but perhaps it would be more accurate if it did, as in my opinion that shapes a person as much as anything (it certainly did with me).
And when I mentioned having the rug pulled from under me, I should have perhaps couched that in some context; there's no family money to bail me out, there's none of that support network which I associate with middle class people (that's my perception, I may well be wrong), and I don't have a professional qualification which would be easily transferrable.
So, in summary; no, I don't agree with the pigeonhole it put me in. I'm just malleable old me.