The "margin" is the gap between VLS and V alpha max (most of the times out of view but you can get an idea if you see V alpha prot).
VLS does not change with load factor, while V alpha max and V alpha prot will increase with load factor. In a pull up or a steep turn the gap narrows as V alpha prot gets closer to the fixed VLS.
I think it would be interesting to see a definition of maneuvering speed from other manufacturers such as boeing.