"Implications" of written words are funny things; they are formed completely inside the reader's head, and may be biased by the person's previous experiences. Again, I didn't see the post, but unless there were some serious always/never-type qualifiers, most folks would take this as "sometimes water falls from the sky", not "water only falls from the sky, and can't possibly come from anywhere else". Given the amount of variables (presentation angle, skull thickness at various points, impact angle), I can't see most reasonable persons taking it any other way. Same with the comments on skull thickness.
If a person is making truly outlandish claims, it will probably become clear to all, eventually; no need to point it out, call them names, or make snide comments. If anything, asking them how to overcome such a problem is sometimes more...instructive (known in some circles as "giving them enough rope to hang themselves").
Bickering about "proof" and "facts" just drive people away from the discussion(s), and eventually, the site, and we'd prefer that not happen.
I think everyone needs to dial it back just a bit, listen to each other, and maybe learn from others' experiences. I know I've had some very weird stuff happen to me, and although I would not necessarily use a one-off as an example or a reason to change a habit or behavior, expanding your knowledge base can be helpful, as none of us has "seen it all", nor are we likely to. A couple of months ago, a guy posted about a weird stoppage he'd had with his Glock, along with what caused it. As it was interesting, I made a mental note of it. Several months later, another user logs-in and describes a problem he's having with his Glock. I tell him to check something, and that was what was causing the problem. He's amazed! I'm a Glock-troubleshooting-Deity! No, not at all; but I do read a lot, and try to learn from other folks' experiences, as well as my own.
Did you see the thread about the fishing guide that shot the brown bear with the 3.5" barreled subcompact DAO 9mm, and killed it dead at spittin' distance? Is this more or less believable than an instance of a bullet bouncing off a dog's head? I know how I'd vote -- and I'd be wrong. Luckily, the guy had witnesses, a camera, and Game & Fish to inspect the carcass.