Not it's not. I've never heard of mojave being called a diluted gene. It's simply a different mutation of the same gene that lesser is a mutation of.
Sure, there is quite a bit of variability in ball pythons, but, for the most part, a normal is obviously a normal, a cinnamon is obviously a cinnamon and a black pastel is obviously a black pastel. I think it is pretty easy to distinguish the differences between most cinnamons and most black pastels, which to my mind makes it a different mutation.
Personally I think they look different and I think most of the time (not always of course, as I mentioned above there is quite a bit of variability in ball pythons) it's easy to distinguish between pewters made with black pastels and pewters made with cinnamons.