Should be mentioned that this was in the 90s with one of the first computer-animated feature films. We're missing the source code for a ton of games from that era as well. I would assume people had learned to have proper backups 30 years later - especially so with the advantage of high speed internet.
This is actually one of the goals of some retro computing enthusiasts: recovering the source code for old games through AI reverse engineering.
I know it's not the same thing because you lose comments, unused prototypes etc, but I still find it a fascinating use of the technology.
A common backup strategy was usually copying floppies/cassettes, because storage was expensive, but companies already used tapes for affordable backups in the 90s. Movie studios should have too.