It's hard to say whether or not they would have been arrested without the virus embedded in the coding. From what we've seen before and how game developers treated this problem in the past, I doubt there would have been arrests. My speculation is that upon keylogging someones information, the developers of the cheat programs most likely committed theft.

Or maybe Bluehole is setting a precedent within their guidelines. Regardless, it is definitely interesting and new within the gaming community.