It doesn't sound like a fine, which would be the result of the criminal case.
This sounds like a civil case--as suggested by the "Civil Demand" language--and it comes from Wal-Mart directly, probably exercising it rights under a state retail theft law.
There are two ways to skin this cat. You could just pay the $250. Or you could consult with a local criminal defense attorney--this isn't a criminal case, but they are the lawyers who are going to know about the retail theft laws--and asking whether the claim is legitimate under Kentucky law. I suspect that it probably is. Which means that your son is likely to have to pay something. It'd probably be cheaper to just pay the $250 than try to fight it. If you don't have the money, your son's wages will likely be garnished.
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