I think it is more a quality control thing. To avoid the problems like in iOS-Store, Android Store, Windows Store and Steam also. And the other thing is, to avoid public hardware specs to soon. To control the information about your new hardware and specs.
Also the thing is, if somebody pays 10.000,- + $ for a Dev Kit or Engine, he/she would not mess around with it, like it could be, if all would be for free.
XBox 360, Dreamcast and so on, worked similar, I think.
And there is a way e.g. to get your Game to Playstation 4 and XBox with GameMaker Studio, but you have to be a registered Dev at Sony or Microsoft and pay a fee to YoYoGames for the Export Module.
But since Nintendo is saying, that every engine with C++ could be used, and the hardware is like an nVidea Shield, I think, that it is more like an special APK-export how it's done for Amazon Fire TV or the OUYA.
I think the problem here is more, that there are not many (if some) games out, made in GameGuru or AppGameKit 2, wich sold as many as some of the Unity or Unreal Engine games. But there are games like "Thimbleweed Park" or "Stardew Valley", or "Minecraft", wich are made from scratch in C++ or JAVA, I think. Maybe they need an Unreal Container or something.
So TGC have to have a game, wich they can offer Nintendo for the Switch, to became a Nindie or something and tell us, if an Export to the Switch could be a real thing in the future of AGK2.
The don't have to say how exactly that works, because of the NDA
But YES or NO, would be possible, I think
