It looks like he doesn't even understand how the karma system works. He thinks users are deleting his threads as soon as he writes them. It could just be an attempt to feign ignorance I suppose, but he does look pretty much like an idiot, so I wouldn't put the chance of it being real ignorance beyond him.
Anyway, as you said, he's just about under default. A few more ratings and he'll probably be sub-default. As long as you're not using "never filter" then you won't have to see him anymore. If you are using "never filter", then you have nothing to complain about.