True, it certainly opens the door to prosecution, although whether it would be in civil court or criminal court I'm not sure, plus the fact that the game content is from various international creators, which makes it even more complicated as license and copyright laws vary from country to country - I've researched United States copyright law on my own in the past (though I don't know everything about it), but I know next to nothing about such laws in other countries.
Last time I checked, this seller was located in the United States, although United States laws on intellectual property also have special, additional rules for "imported" or otherwise foreign works that originate from other nations (which effs-up the math even more, into a gigantic legal equation).
Do we happen to have any lawyers who are in this forum? Don't be shy, raise your hand and shout!
As a side note, I noticed in a recent news report about the very first major lawsuit over an open-source project license violation - I don't remember all the details of the article, but somewhere in it it explained that such lawsuits apparently are quite rare. (If I'm remembering correctly, I could be wrong.)