I am not surprised, and I think this says absolutely nothing about the viability of pirating 3DS games.
For those who don't understand, the DS's security was entirely cracked and companies started releasing cartridges that (to the DS) seemed to be entirely valid DS games. Nintendo made the 3DS backwards compatible with the DS and, as a result, when it has a cartridge which (to the 3DS) seems like a valid DS game it will treat it like a valid DS game. Nintendo couldn't prevent these cards from working on the 3DS without also eliminating backwards compatibility with the DS.
3DS games are (probably) a significantly different matter because Nintendo (probably) improved the security on the 3DS' cartridge making it (potentially) significantly more difficult to create a cartridge which appears to be a valid 3DS cartridge (to the 3DS). There are several ways to do this, and the most straight forward way would be to design your cartridge to have simple processor, a private key build into it with the public key inside the signed game image; and to validate the game you would pass the cartridge a value, have it signed using the cartridge's private key and return this value to the system, that value would then be unsigned using the pubic key, and if the original value and resulting value are equal the cartridge is valid. As long as the private key can not be extracted from the cartridge (a difficult but not impossible problem in itself) it should be nearly impossible to copy games unless you find a way to sign game images yourself.
