You'll never take me alive nintendo! Splatoon just isn't good enough to get me to close the game and lose my unlimited supply of swords and rockbreakers!
I don't remember where the setting is within the Switch, but if you turn it off the console requires the user to accept any new update downloads rather than automatic. I am still on 1.1.1 myself. Though admittedly, I haven't closed the game out either lol.
I figured by the time I had accomplished as much as I had in the game before duping, I saw absolutely no harm duping for the remainder of it. We here for exploration and the small tidbits of story at this point.
I think that I or my kid accidentally allowed the update, so I can't dupe stuff anymore, but thankfully I have something like 40k rupees so I'm not necessarily suffering.. I just wish I could dupe some lizards and stamina mushrooms ;_;