I was talking about this with kord, and I gave him a suggestion that I don't know if he passed it to you Cannon.
Could it be possible that when someone use F1 or Alt + F4, the consola send and message warning the people close to him. That could give you some time to A) Blow him off, B) Take screen shots, C) Don't get pissed before he disappears.
I've seen in other servers that they were using a similar system. When you F1'd near to someone, it blow you off.
Now, that could be harsh to some people, as they have expressed here.
But, how if you make it to lose just the cargo when you are close someone. In that case, traders who get DC'd won't lose their cargo (if they are not close to another player), and people in battles won't get hurt neither.