This is absolutely ridiculous logic. He was doing far more important things at the time than prototyping a calculator, even if he could. These were likely 10 minute flash meetings where he gave direction. This was about time, and time alone.
Apparently for Jobs this was very important to him (he was very picky about details anyway), and if you sum all of his time wasted on each interaction I can see how they are equivalent, he just changed a few UI things anyway.
