> I would love to know what happened on Nintendo's side.I suspect it's just a normal, regular software bug.
SSL code is often complicated, and the faulty code probably passed a bunch of tests. As the software update was for a decade-old product, which had been discontinued for 4 years, the people who were best placed to spot the new bug had probably already moved on to other projects.
Why mess with the SSL stuff at all? I can't say for sure, but SSL makes it easy to accidentally create a time bomb by, for example, hardcoding a certificate with an expiry date 10 years away. Or a console might have special requirements. For example, a user can leave a device in a cupboard for 5 years without turning it on, so the software update procedure needs extreme backwards compatibility.