I just got back from vacation and Bluebeard's still alive! I had to fast him for a week because the only people I could ask would have forgotten anyway. I know that bettas can theoretically go for a couple of weeks without food but I was still nervous about leaving him. I was so glad to not find him floating in the tank! Instead he was just hungry!
On a side note, I had bought sea monkeys, planning to feed them to him but when I saw the one I put in, swimming around, confused in the strange tank, I just had to take him or her out! (I'm a vegetarian if you can't tell). So he'll just have to stick with regular food.