I hope I never have to work with someone like him. He sounds awful.
In a way I agree - someone programming like this right now without very good cause would be a bit of a nightmare if you ever had to tangle with their code. But it really was another world back then.
They were so resource constrained [1]. That "drum" wasn't the hard disk, it was the memory! Think about waiting for the rotation of a drum for each instruction read. Then the actual capacity of it was only 4K. The laptop I am typing this on has about 32 million times more memory and I don't like to think how much faster it is.
You either used clever tricks, or you wrote very limited programs. There was no room for any overhead. The author of that story wasn't astonished by clever tricks, just the degree of cleverness.