First, let me correct my mistake. There's nothing wrong about being open source. Most cases its a good thing. But in an security product? Not sure about that one..
As for it being unique..I couldn't say. But thats because I have never, in my years dealing with websites, felt the need to use an antivirus for my sites so therfor I have never looked into this business part. Now that being said, that was my personal opinion.
However, these days I wouldnt be too surprised if there is quite a bit of market for it amongst new and upcoming web devs. Since "anti-virus". lol