That was clearly in a joking tone, but the idea is not a hole at all, the math even adds up.
The difference between full calories per day and 2/3 calories per day is literally ~800 calories in that spreadsheet.
The calculated time for those 800 calories is about 7.7 hours which rounds to 8 hours.
There's 24 hours in a day. 8/24 is 3.
That's 1/3.