That's just the regular skin. The viewpoint replaces that with a single dot, which is easier to see in most cases, and it also gives you an idea of EXACTLY where you're aiming, not just sit there and think "well, I think I'm on him, but I can't really tell...here goes...nope, I was wrong, oop, I'm dead.."
You can probably ask the creator of it to make another customized one, with the iron sights with it, but I think that defeats the purpose...
And Mil, send me that .vtf file with the new scope, I want that bad boy lol