The issue is that it is an incredibly dangerous precedent.

There are already a decent number of emulators where the devs have done a good enough job making plausible deniability but it is still VERY obvious they looked at the "leaks". But if it is decided that "used a pre-release leak to develop code/support" is a no-no, then everyone knows to not do a 0-day update. But they start getting wary of doing day 1 updates because... it is still pretty obvious that they had that ready to go.

Which... could even be nintendo's plan. The example I always like to use is Mass Effect PC. For those who were likely born well after that, MEPC was INCREDIBLY anticipated because we were all cool and didn't need Mass Effect because Bioware were traitors who abandoned PC but... motha fugging Mass Effect. It was one of the early activation model Securom games DRM wise. And the warez groups did a bad crack that broke like two hours in (which meant they already "won" the release and fixing it was low priority). Which led to waves of pirates (self included) rushing Best Buy because we needed it NOW.

So if this makes for "okay, we can't add support for this game until a week after launch", that does wonders for sales figures. And, in a uniquely nintendo way, it avoids the ever more popular "So... this runs at like 10 FPS on the switch and 120 FPS on a potato laptop" problem.