It goes even further than that.
Firstly, opening the game like this person is in the video is only possible with a brand new unit on system version 1.0.0 that has never been connected to the Internet. Because of this, opening it is pretty hard to replicate, unless if you have a completely brand new Switch. So, even if the system’s internal date is on July 11, it still won’t open if the system version is up to date.
The thing is, it’s not supposed to be opened.
The hidden Golf game has been described as an omamori, which, in Japanese culture, is a charm usually bought at shrines that offers spiritual protection and good luck if you keep it close to you. Sometimes they’re made of cloth, and look like a tiny bag, which can contain a written prayer. People often tie them to something like a purse or a backpack, so that it’s always with them. Here are a bunch of different ones:
Omamori are not supposed to be opened, as doing so is said to remove its blessing.
Seeing as the hidden Golf game on the Switch is so difficult to run under normal circumstances, it’s probably not supposed to be opened in the first place. It’s likely meant to represent an omamori in Iwata’s honor. Its very fitting, because of how portable the Switch is, since people are likely to take it with them like they would with an omamori strapped to a purse or backpack.