"Please tell me what part of the source code infringed copyright?"
Judging from your question, your confusion about why this is illegal stems from two problems: you're unclear on both the law in general and the charges in particular. In this case, there is no complaint that the code has been improperly copied from someone else. Indeed, the code may well be an original work, freely distributed by its author, and being used in full accordance with his wishes.
However, copyright law covers more than that. Here, the complaint is that the code exists principally and primarily to violate the law, which is a violation in its own right. In this regard, publishing it is a bit like distributing sawn-off shotguns, which are generally illegal regardless of what's being done with them.
Judging from your question, your confusion about why this is illegal stems from two problems: you're unclear on both the law in general and the charges in particular. In this case, there is no complaint that the code has been improperly copied from someone else. Indeed, the code may well be an original work, freely distributed by its author, and being used in full accordance with his wishes.
However, copyright law covers more than that. Here, the complaint is that the code exists principally and primarily to violate the law, which is a violation in its own right. In this regard, publishing it is a bit like distributing sawn-off shotguns, which are generally illegal regardless of what's being done with them.