Marydoll, the "OP" started by describing her DIL and family as "posh" in her title. I haven't introduced it.
I understood your post. However, we only had your report of what you wrote, not the actual post. If your post only contained what you reported on this thread, then the person who replied was, as I said, wrong; you were not using inverted snobbery.
However, you complained that you had been described as an inverted snob on another thread. Your interlocutor is not here to defend themselves (the reason why it is against the rules to have a thread about another thread). In fairness, I suggested that, had you, in your original post, turned your experience against others who did not have it, you may have been guilty of inverted snobbery.
We don't know what was actually said. There are two possibilities. You are complaining because I tried to be fair to both parties, as we had only heard one side.
The poster complaining about the use of the word "drawing room" did not say it was uncommon. I agree. It is. However, that poster described its use as "weird". I asked what other word she suggested the room could be called.
Her post (and yours) did seem to have an angry or unpleasant attitude or way of behaving caused by a belief that one has been treated unfairly in the past. That is the definition of a chip on one's shoulder.