What I have heard is that they planned to do such an FX shot.
They plan many FX shots for all the movies (like Data knocking the soldiers off the cliff and tagging them, from Insurection--filmed but never completed or inserted into movie.)
But many FX shots are never completed for various reasons. The idea that they spent the $ to complete the shot and then inserted into Generations for a single print and then lost it--is silly.
Not 100% impossible, just very unlikely.
What's more possible? Mis-remembering.
The 'letter to the editor' triggering a false memory--also possible. Certainly more likely than being in one print and getting lost forever.
It's not 1927 Metropolis being hacked to pices and never being 100% whole again--it's a 1994 major motion picture.
Shoot the FX people would have commented, "we completed that shot but it never showed up!"
Even if it was two seconds onscreen, it would have taken a few man hours to finish.