I'm a little surprised at how many folks are out with their pitchforks. It's easy to say "fork it over" when it's not your money. Especially when at the center of it is an item that has turned out to hold little value. Was it an ironclad conditional agreement? I don't know. Personally, I wouldn't have made an agreement like this in the first place (either as a seller or as a buyer) since it can easily have the potential to go sideways if someone isn't happy with something.
After seeing private disagreements being made public many, many times, more often than not, the person who posts about a private matter does not end up actually being the fully wronged party.
I know a lot of people practically salivate at the prospect of a good drama and controversy and like to pick a side and scream for justice. I'm guessing since the buyer has been on the forums for a little while, he is aware of the kind of show that usually goes down.
Personally, I usually like to hear both sides. A dispute usually takes interesting turns after there is a response from the other party, and I've been surprised more than once with what additional information brings. So, I've learned to try to reserve judgement before all the facts are in.