I don't know if this was the author's interpretation, or if this part was in the shooting script, but changed. Does anyone know?
I'd like to know the answer myself. Recently I had been rereading the scene where Kirk asks Scotty to fix the main energizer but Scotty disobeys because of the lethal radiation levels in the energizer room.
It has the feel of a deleted scene and I believe that Vonda McIntyre based her novelization on an early script but some scenes were altered last minute prior to shooting. Admittedly, Scotty blocking the turbo lift and holding the dying body of his nephew added drama and a surprise effect to the final scene.
"In-universe" I think Workbee
provided a sound and very good rationalization.
Of course I wonder if Scotty had been done with all the critical and instantly required emergency repairs but that's a different story.