As long as the tool isn't proprietary it's acceptable. If I can go to a hardware store and buy the interface tool then it's fine, but it's not fine if I have to get it from a special manufacturer or if it's proprietary.

In the case of Nintendo I gave; Nintendo have their proprietary tri-headed screw. They do not make The tri-headed screwdriver publicly available, of course companies have copied them and so you can get one that way, but they're not official, so my understanding is that that would not be acceptable. Nintendo would have to officially release the tri-headed screw design, and they're probably just more likely to switch to a different already public screw design.

I also think they are allowed to just glue the batteries in as long as they have pull tabs. Which is probably the better option.

My point is Apple won't be allowed to just come up with some brand new screw design that no one else has ever seen before. Unless they open source the screw head. In which case I guess it doesn't matter. But they're not going to do that because there would be no point.