Why would you leave a neutral, because you can? The buyer received the item, didn't he? I realize everyone wants to get their item right away, but everyone always wants to make someone pay for a mistake. Seems a bit ridiculous to give a neutral since you have the opportunity with the star ratings to express your displeasure with the shipping time. (detailed feedback for seller)

When I sell something and someone pays right away I send right away. If you're gonna send two weeks after the auction ends then state it in the auction. You're not hurting him by leaving a nuetral. It's not a negative. You're letting other consumers know that they might not see their cards for 2 weeks if you buy from him. Thats what feedback is there for.