Lol, I can't believe this is still such a big deal lol. You are suppose to put in the pen one way, that's it. Common sense and logic should be enough. You accidentally put the pen in backwards, it's your fault, the pen is not promoted as a reversible pen. You accidentally drop the phone in water, too bad, it happens, but it was the users fault, the phone isn't promoted as being waterproof. I don't own the Note 5, and I don't like it for various reasons, but never once did I try putting the S-Pen in my Note 4, bottom side first, not even by accident. I always found this so hilarious to think people were doing this. This is really so stupid lol.
It is just like a replaceable battery. If you buy a cheap one online and it fits on your phone, but your phone burns up, it's not the company's fault, regardless if you know if the battery is fake or not. Should they remove replaceable batteries to prevent people from doing it by accident? No. An S-Pen is even easier, pointy side goes in first. lol.