Encoding the name of the buyer in the MP3 is not DRM. It doesn't restrict your usage of the media in any way. If they do that, I fully support it.
I still prefer my MP3s name-free, but that only means that I would pay more for name-free than for named MP3s.
I wonder what the laws are on selling the track and then deleting it though. Is that as legal as selling a cd, or do you get sign some sort of legal agreement when you purchase the track? I've never purchased a single track online so I don't know much about that.
Also, maybe you could just remove the information from the file if it bothers you.
You can probably imagine how silly it would feel to make sure you lose your MP3 after selling it, and what would you even ask for the MP3? Fiddy cent ?