I understand that the payment was reversed by the credit card company, but it's hard to believe the stolen part.

Who steals a credit card and then buys an extended license for an unpopular stock file, when they can get the exact same AI/EPS files with a regular licence, which is many times cheaper? If they use the subscription option, then they could get tens of vector files for the same price.

It really just sounds like someone changed their minds and demanded a refund through their credit card company. I would expect thieves to have lot better ways to make money from stolen credit cards. I wouldn't expect them to benefit much from stealing unpopular stock photos and uploading them on some random website - the juice isn't worth the squeeze.