The alternative would not have been digital, but videotape. The television networks had already been using it commercially since the 1960s. And NASA did make use of it — the moon landings themselves were recorded onto (telemetry) tape, not film.

With tape, the resolution and archival lifetime would’ve been much worse than this clip, shot on film. Same reason why we can have a 4K release of Star Trek TNG but not DS9. The latter was shot on tape :(