I know you've had some time wasted but I don't think you should start bombing people's feedback because they decide they don't want the deal anymore. At the end of the day, you've still got it shown as for sale or uncompleted which means anyone can offer on it until you change the advert.
It was accepted when he placed the offer. I agree with you on the whole however this is the 5th time. If you're not committed, don't place an offer and carry on communication after it's been accepted. I'm now stressing this very clearly