Obviously there are a few things going wrong right off the bat. This is why we harp endlessly about reading the rules. If people would sacrifice just a couple minutes of their time to read, half of these problems wouldn't even be problems.
A. The buyer tried to change canoes midstream. In the rules it says clearly, if you do not want the item or can't afford it, don't buy it. Period.
B. jumping the gun as you put it, by filing a paypal claim is a very emotional reaction to something that can be easily resolved with a simple email or phone call. A claim should be saved as a last resort when communication fails.
If the story is as you say, it's likely that not very many people will be willing to do business with this person in the future. Shame people don't think before acting.