Here's the thing: Many popular live albums are pieced together from an entire tour or longer. They become more like greatest hits albums that way, as the best performances of each song on the tour is often chosen for the album.
That's not the case with the album I chose. If the two performances were on separate discs, there wouldn't be any contention of its validity. It would simply be legal, no questions asked. I fail to see why its release as a double album makes it illegal. If live albums are legal, and double albums are legal, than this album is legal.
If for some reason Slim disagrees, would I be allowed to take one of the discs, even though they are not available separately? It would then become a live disc that meets the strict interpretation of the rule, which is not even in the original post under the rules section.