Hi there
I found out about this post on Heart FM's website. I wanted to start by saying I'm also a child of an alcoholic so totally get where you're coming from on this. We are super sensitive to it, what I will say is that those commenting with little to no experience of alcoholism, alcohol misuse etc, will probably see it as an over-reaction.
I see the comments about how much alcohol is in a sip, what harm could it do etc etc. This is a very simple view of it and not entirely relevant.
You were right to do what you did, you didn't like the environment so you left. You didn't say anything to the person, just made your excuses and left. That is very polite and reasonable in my book. Had you have had a verbal discussion about it, then I can understand some of the discussions. Yes it is the persons house and yes it is their child etc. I'm really not sure that has much weight either, because that point to me is saying people should do what they like in their own homes.
I'm not sure we can say that across the board, it's not OK to do a lot of things even in your own home.
My point is this. What would be the purpose of giving a child alcohol? No matter how much or little. What is the parent/caregiver hoping to achieve? There are plenty of other drinks a kid can have, so what's the rush and need and reason for alcohol?