You might be correct, though NEC would require the grounded conductor to be identified with white or gray all the way through the system.
What he may really have is possibly the conductors marked blue should be marked white and the conductors marked white (that are on load side of the service disconnect) should be marked green.
Many get confused when the grounded conductor is not a neutral conductor for some reason. It is kind of a rare situation so that doesn't help.
But remember, this is a “1950s” installation.
It’s had 70+ years for anyone to screw up with tape colors and wiring.
![Grinning face with sweat :sweat_smile: 😅](https://cdn.jsdelivr.net/joypixels/assets/6.6/png/unicode/64/1f605.png)