Let me start with: The whole point of ebay is to sell or buy something, not to have an open aution. If it was to have an open aution, then there wouldn't be a "Buy it now" option.
IMHO, it should have stopped with his first reply. He showed that he could be an A**hole with his first response.
And all it did by responding back was get you to respond with something you knew was wrong.
But it felt good to rant back, didn't it?
Many of us would have done the same thing.
And NO, it wasn't wrong for you to ask if there is a "buy it now" price.
When I sell something on ebay, I state that there is not a "buy it now" price so please don't ask to end aution early. And I still get asked. I just shake my head and leave it at that. Yes, I could reply back with "Can't you read" like I've seen some sellers do, but I'm not perfect either.