The technical protection measure is the digital certificate and possibly even the proprietary game cartridge form factor.

(2) No person shall manufacture, import, offer to the public, provide, or otherwise traffic in any technology, product, service, device, component, or part thereof, that—

(A) is primarily designed or produced for the purpose of circumventing a technological measure that effectively controls access to a work protected under this title;

(B) has only limited commercially significant purpose or use other than to circumvent a technological measure that effectively controls access to a work protected under this title; or

In my opinion (A) is violated because the non fungibility of the game cartridge is violated by copying the certificate to present an inauthentic cartridge as genuine.

(B) is pretty straightforward.

But I don't know, maybe I'm wrong, maybe Nintendo lawyers are wrong, and this guy could've fought this specific charge over a technicality. Reminds me of how Sov Cits always get out of traffic infringements because they're "traveling".