I didn't look closely at the picture at first but uh.. I think you're right. That's definitely not filled correctly, and if it was, it's definitely a defective tank.
That said, I fill mine from the correct end, and I see the exact same sort of leak. Stems from where the cone meets the battery and spreads both directions, just as you see in his picture.
I can't tell from the picture, but I think if you filled from the top, you would know something is wrong as it wouldn't vape correctly at all would it?