Something to consider though, it’s not an altogether unlikely an explanation that the people writing these books are as much a fan as we are, and specifically sought out the Legacy clip to use for the book. You could even say that this is the Occam’s razor explanation - the shot from Legacy is arguably the highest quality clean still of that shot out there, which is why it might have been used.
Important to note as well, the writers do not technically work for LFL, they work for Haynes publishing.
The Authors said:
Because Lucasfilm considers the revised version “canon,” I didn’t know whether they’d allow Haynes to use the earlier still frames, but I’m glad that they did, simply because the original version more clearly illustrates the X-wing’s S-foils in operation.
I suppose it is possible that Haynes got permission to use images they just happened to have found. Hell, maybe the authors themselves found it. However, there is a slight color change in the Death Star, which I was taking to mean that the rough Legacy preview on Vimeo had been further tweaked.