A bit too close to a troll, but there is a germ of a good point, which is whether its ethical for Nintendo to profit from this code. I think the answer is clearly yes, for the simple reason that the author chose to release his code for the world to use. Most projects will die in obscurity, unused (and unmourned).
There are a ton of project owners who would love nothing more than to be used by a big, popular platform. That's a pretty big win with hardly any risk. It means their thing beat out something that could have been made in-house by the world's best devs. Can you imagine discovering that your little thousand-star github library is present in, I don't know, Gmail? Presumably, at the very least, it means an auto-hire if you apply to any of the biggies for a very high total comp.
(And if you refuse on principle to cash in on that endorsement? I say good for you and I would like to hire you to be on my "wizard council". These are people I subscribe to to be diligent, principled, skeptical, and open about any software update I consume. This would include, BTW, a holistic definition of "software" to include firmware, FPGAs and so on. Please talk to me like an adult about InfoSec! Thank youuuu!)