This is bad. Because,
a. Switch 2 can get bricked when Nintendo wants you to upgrade to the “Switch Tree.”
b. If you discover a purely unused switch 2 decades later it will be useless. It’s bricked unless you get that Switch 2 update.
c. It all ties to that Nintendo bricking terms of service terms.
Isn’t the thing with this that the Switch 1 compatibility layer isn’t on the factory firmware since it was a later developed piece of software? That’s probably why it’s asking for an update, as these units were made months ago (firmware 19.0.0 according to that leak out of Russia, and we’re on 20.1.0 on Switch 1 at the moment). I remember on the box they showed on the Nintendo Today app, there was something in the fine print about needing a system update both to use Switch 1 games and to use MicroSD Express cards. Very few if any people have a Switch 2 with a Switch 2 game cartridge at the moment, so they’re going to run into this when they run a game. The only way to rule this out is to put in a Switch 2 cartridge into one of these systems on the factory firmware, but as far as I know even now if you put the cartridge in it will run the game.
Edit: Can confirm that it is the case you need the Day 1 update to play Switch 1 games from one of the crunchiest images on the internet (it was the best one I could find of the box)