While I agree with your reaction, and would feel the same myself, they didn't buy the code, they bought the repo, it's stated quite clearly in my opinion.

Typically I would find this kind of PR stunt irksome, but I don't begrudge the little guy doing what they can to get some attention on their product, and it's an interesting read non the less since I hadn't really considered the logistics of buying an open source repo before.

I suppose a better way to put it, would be to say they bought the stars/links/name, which I have mixed feelings about.