Probably because most people aren't considering that this concept art could have very well been drawn before DisneylandForward was fully approved (like the other piece of concept art), so at the time Disney was leaning heavily toward this location and generated the concept accordingly. But now that DLF is approved and they didn't reveal a specific location at the expo, it is very well conceivable that they are still internally debating if they want to continue with it in the backlot or move it over to the Simba area.
I'm not trying to argue that it is DEFINITELY going to Simba, but that it is still a chance, no matter how slim. I also do concede to the fact this piece of concept art had the backlot in mind when it was created. It's not hard to see that. I will also concede to the idea that at one point it was definitely going there and that's why all the rumors point to that......however......I also know that plans can always change at the last minute when it comes to Imagineering. At least that's what everyone here says when they think they are right but want to be open to the possibility that they are wrong. Just in case.