If they’re really concerned about credit card fraud, they could use a prepaid credit card. That way, at worst, they can only lose the amount they preloaded on the card. Would cost a bit extra in fees, and they should check the exchange rate used, best to buy a card that can be loaded with Thai baht.
I’d take the risk and just use my usual credit card, regularly checking the card online, just as you should at home, where you can also be the victim of fraudulent card use.