I think you've misunderstood the point. Terawatt-hours is ambiguous, without specifying a time period.
In particular, Terawatt-hours can be converted to Joules. To say that humanity's energy usage is X Joules is meaningless without specifying the time period that that energy is used over. For example, it means very different things to say that humanity uses 5 TWh per day than to say that humanity uses 5 TWh per year (versus 5 TWh since the dawn of recorded history!).
That's not the context that everyone else is referring to. They are referring to this:
"[NERD NOTE: A terawatt is a trillion watts. The entire planet’s electrical consumption is right around 5 terawatt-hours. One TWh (terawatt-hour) is a constant flow of a trillion watts of electricity for a period of one hour.]"
The argument others are making (which I think is correct) is that it is meaningless to say "The entire planet’s electrical consumption is right around 5 terawatt-hours" without specifying a time frame over which that consumption occurs.
In particular, Terawatt-hours can be converted to Joules. To say that humanity's energy usage is X Joules is meaningless without specifying the time period that that energy is used over. For example, it means very different things to say that humanity uses 5 TWh per day than to say that humanity uses 5 TWh per year (versus 5 TWh since the dawn of recorded history!).