Just so you know, the fan model it's supposedly based on isn't Cyberhand's model, but a model made by one Dr. Frosty, which is slightly different from Cyberhand's version. (If Dr. Frosty is Cyberhand's steam name, feel free to let me know)
Since no one has done so yet, here's a comparison of all the versions of the MoUP, side and front views where possible. Cyber-hand's model will be used as well since there are better pictures of it than the official.
Real edition (lines by cyberhand for his model, but this is the only pic I could find that had it straight-on, rather than at an angle)
The Dr. Frosty era, for which I will be using these pictures (from the link in the first post of this topic) to illustrate the shape similarities
The sticker incident
The big point of difference is the two side horns. On the original, they come down to an angle and go in.
Same story on Cyberhand's model
On the fan edition, they curve inward
The sticker does so as well.
Still not convinced? Well, let's look at the center section
On the original, the center ledge goes downward and ends at the lower center of the forehead circle
You can see this as well on the cyberhand piece. I think it slopes down a bit more on the official, but That's just me.
Dr Frosty, however, had the center ledge level, and it ends at the top of the forehead circle
And as for the sticker?
Flat ledge, top of the circle.
But, if you're still not convinced, let's do a side-by-side comparison. First, the sticker to the fan model, which @ThatGuyAtTheEndOfTheRoad already did.
But here's sticker-to-original (not a very good picture, I'll admit, but the best I could manage)
And sticker to Cyber-hand (which turned out much better IMO)
Obviously, there's going to be some differences due to these pictures being at different angles, but the differences in the ledge and horn shape are too big to ignore, while the sticker matches the fan model almost exactly.
Conclusion: the sticker is absolutely based on the fan model. I am 99% certain of it.
Does this mean that Lego owes something to Dr. Frosty for using his design, which was in turn based on their design? No, they do not. Not at all. But as to whether they did actually use it as a reference, they certainly did.