That's an interesting anecdote.
I fly first class a fair bit (10-12 flights per year), and children in first class is pretty rare. When I've seen it, they've never been rowdy. In fact, my experience is that its usually really quiet, which is one of the things I really value.
Maybe i'm just the luckiest person in the world. But its never happened to me and I fly a moderate amount to have some sample data.
I will concede, that flight rowdiness in general is very different based on time of day. The afternoon is the worst. Fridays and Mondays are the worst. I love night flights, to the point where I prefer them. Everyone is so much calmer on red-eyes.