I'm pretty sure at this point you're not really trying to prove anything, just trying to be right. If your first two points are "you're wrong there and you're wrong everywhere else" I'm inclined to ignore your statements and pass them off as really bad insults.
Then you have the burden of proof, and here we are. So far what you've presented I've refuted with the idea that these are actual design elements that could not be 100% incorporated into a sticker smaller than my thumb produced by the LEGO Company. I'm not saying LEGO is morally perfect and would never do something like that, but the whole idea that they accidentally went online and found a image completely outside of their legal usage when they have truckloads of reference material and physical models to examine with their own eyes is incredibly silly, at best.
There. It was not as important to the points I brought up, because I was focusing more on the sticker and the official model. But, since you're using that as a scapegoat to state that I'm prejudiced to LEGO, here you go.
If that was the case, I woudn't be posting in this topic. ;]
Firstly, they don't have "Fan Insight"? If you mean that they are unaware of what occurs in the fan community, why is this sticker even in the set?
Secondly you've just switched your argument from it being accidental to it being 100% purposeful. I'm going to assume you've switched to this one.
You're right. It has a lot of similarities. But nothing in the sticker's slight redesign proves that LEGO used this fan product, only that they outlined some of the different parts of the mask, such as the slopes on the two front spikes of the MoUP:
While it's interesting that they decided to this, it's a bit ridiculous to jump to the conclusion that LEGO blatantly stole a fan design of their unreleased mask due to some aesthetic changes.
Well, to each his own.