They’ve given the option in case the buyer has a valid reason to request a refund. Just as an example… they buy an HTML version, but wanted a Wordpress version… they then contact you to tell you, and you both agree that once he has purchased the Wordpress version, then you will provide a refund for the HTML version. Happy days… everyone’s a winner.
In some cases, they might not have a valid reason to request a refund, so at that point it’s up to you whether you provide one or not. I appreciate that nobody wants a one star review, but it’s probably best not to be ‘held hostage’ over a negative review… you might set a precedent, and if the word gets out that you’ll issue refunds readily, then it could cause you problems down the line. I guess one has to take into account how many good reviews they already have, how a one star review will affect that, and whether it’s worth taking the hit.
What was the excuse the buyer gave, just out of interest?