And why are we so worried about passing on Windows Viruses, doesn't everyone running Windows HAVE TO run AV software. They would be nuts if they didn't. Viruses and malware have been and will always be problems that windows users will face. Just like you said.
I suppose it still remains a personal choice, albeit quite a gray area. IMO, knowingly passing on a virus to another computer, and damage results, could very well be interpreted as malice and then be subject to criminal charges. I am not an expert on it but even if criminal law does not apply, possible civil action certainly does apply. Suing someone over damages could become more common in the future.
I know I would sue the jackass.