The way I understand it, your citizenship is irrelevant here. If you happen to visit South Korea, they can usually prosecute you for a crime you allegedly committed on the internet while abroad. Seeing as you'd be charged with creating or distributing a ToS-infringing program, it's likely sufficient that at least one person located in South Korea received (or could have received) a copy of that program for the crime to fall under South Korean jurisdiction.
Extradition is more complicated; depending on your country of origin, the crime you are charged with must also be illegal under local laws in most cases.