Or that he is running HVAC for his 2000 sqft house, vs running HVAC for his 180 sqft office space (where 180 sqft are dedicated to him out of some large space shared with others).

Part of it is that he's comparing his work-from-home AC expenses to his work-from-office gas expenses. He's not factoring in the company's office AC bill, because he doesn't pay it.

Also note that, at least in my case, I've got a cubicle farm at work. I can't just up the temperature for my 64 sqft cube; I have to up it for an entire quadrant of the floor.

Big family house in the suburbs with aggressive demand scheduling (ie, we let the temp float a fair amount when nobody is home) versus high-efficiency car.

Could be, but it's also likely that 1x big HVAC is more efficient than 10x smaller units.