I agree with it probably just being preemptive legal defence. Even their current used solution, being fully locked out of the Nintendo servers, is probably enough to be seen as "rendering a console partly or fully useless" should it ever need to be litigated in court. Especially with so many games and functions being online, digital or card key only.

But I really doubt the 'burning an internal e-fuse' idea. Mostly because they can already achieve enough in online service and software alone that they wouldn't need such a fragile solution. They would really shoot themselves in the foot if they did. They would have way too little control over it themselves. A sudden swath of consoles bricking on a hot day would give them a bigger headache than the Joycon drift issue ever did. If not in the US, most definitely in the EU.