No, it's just a rather dubious* way of representing the overal "net lift" after accounting for tailplane download and the way tailplane download is a function of static margin. The idea is that if you looked at the maximum available lift using Cl(max) and the wing area as the reference area it would yeild a number that was significantly higher than the "real" maximum lift, because the "real" maximum lift would have to take into account the tailplane download. So they produce this numerical method which is based on the concept of calculating the tailplane download/static margin relationship, and then producing a function showing this as a Cl(max) to static magin relationship for calculation purposes.
The *actual* Cl(max) and the actual lift slope would remain exactly where the polars said they were, which is one of the reasons I don't like this simplification. Another is that it continues to reinforce the myth that the behaviour of 3-dimensional wings can be accurately described using just the 2-dimensional section data. Which is another way of pointing out that there are a few dozen other parameters which could just as validly come into play here rather than just CG position.
* in that while it may be numerically arguable it does not describe the physical reality