I did not see her comments as insulting. A few of us understood as she intended.
When people don't understand as you intend, don't you change your approach instead of carrying on in exactly the same way so that they may understand better?
A few of us obviously didn't see as she apparently intended, but instead of trying to help us understand, she went along in the same vein which only compounded the problem.
OP--you're good. You earned the upgrade, your child is part of your travel party, he/she can go in first class.
As for all the other commentary, my take on it is that people who can afford to travel in first class are not going to suddenly start buying coach tickets once they reproduce. I sure that there are many, many kids who have only ever flown first class. If I were rich, I would only fly first class and my kid would be coming along with me.
I missed this early, but I also agree with it. I'm sure there are going to be places I won't take my children once I have them, but if I can afford first class then I won't suddenly fly coach just because I have a kid.
She did try to explain, but only got some more misunderstanding posts. It appears she backed out of the thread b/c some of the posts to her, I felt, were quite rude and some bordering on mean questioning her character.
Sometimes one must look at the intention. I don't think she intended to be rude. I understood exactly what she meant. I think sometimes people look for offense when none is intended. Just as she said, I expect there to be better behaviour in an expensive restaurant and I expect an experience to go along with the price. I don't expect to see young children at Chez Expensive and if I do, I certainly hope the parents take great care to ensure they are properly behaved and don't ruin it for others. The same with Business class. I have a greater expectation of a better experience than economy due to the premium price paid.