Doesn't look like marring from having dirty towels unless he had a small rock imbedded in the towel or something, which I guess isn't out of the question.
Depending on how deep the scratch is it may polish out. Really depends on if it's gone through the clear. If your fingernail catches in it then polish probably won't be enough. It will make it less obvious in most cases, though.
Best advice is to call a detailer. A real one. Someone who does paint correction, not a "car washer."