I see no problem with it being a bitcoin payment, it was for a dollar amount. No different to me making a transfer to his account in UK Pounds and his bank transferring it to US Dollars.
You seem to be confused so let me clarify again. If and when you get a judgement you can locate a bank account and get the sheriff or police to put a lien on it thereby freezing it so you can get the money. You can't do anything to bitcoin without the person with the private key willingly transferring it you no matter how many judges issue a judgement in your favor.
When the merchandise was bought they had equivalent costs in US Dollars to Bitcoins. So you could request payment in the fiat value instead of Bitcoin. This would be more simple especially for the judge, as Bitcoin price isn't stable these days. So in my opinion it isn't an issue.