The statement isn't necessarily false. You didn't show how the statement is false.
More time spent staring at a text editor (or even spent pounding on a keyboard) does not mean that you produce more. Maybe if your production metric is characters typed you produce more, but in terms of usable features there is going to be a point of negative returns on time spent.
I think he means that when you are in a really good groove, you can be way more productive (and happy to keep working).
I don't know about anyone else, but I can definitely relate. This is 100% about your state of mind.
Happy code comes from a happy coder :)
More time spent staring at a text editor (or even spent pounding on a keyboard) does not mean that you produce more. Maybe if your production metric is characters typed you produce more, but in terms of usable features there is going to be a point of negative returns on time spent.