According to Twitter user @SciresM, who is a data miner himself, the NES Golf game has been removed from the Switch as far back as the 4.0.0 update. This means that anyone who has updated their consoles as far back as 18 October 2017 will be unable to play the hidden NES Golf game.
In its place, the Golf game has been overwritten with a bunch of garbage. As to why Nintendo might want to “erase” the easter egg, that is up to speculation. If you wish to speculate you can join the rest in this Reddit thread and chip in your views.
Switch update 4.0.0 stubs "flog" — all code to launch it removed, and flog executable overwritten with (signed) garbage. https://t.co/6Q47sHn7Ud
— Michael (@SciresM) December 24, 2017