Copyright of code doesn’t work that way. Now if some idiot goes and uses that code in a game, yeah, they’d have a rough time in court.
If Nintendo thought there was infringement already, and wanted to prove it in court, there are means to securely prove it with redactions and NDA’s and so forth as it would be considered trade secret.
I think they may be making a joke about how flimsy Nintendo’s patent case is, since the alleged patent was filed this past July