Interesting but kinda beside the point.
So he SWAGs the per year cost of propane at $590 per year using his assumptions.
$25 bucks to do a Blue Rhino exchange (which is maybe 15 gallons of fuel).
So he thinks I'm going to go be using my grill so often that I'll do 23.6 swaps per year?
How many propane swaps/tanks do you do a year? Do you even hit double digits? I don't.
Fuel cost is a minimal consideration. If it was just about the fuel and grill acquisition price, we'd all just cook using your kitchen stove/oven. By far the cheapest.
People use a gasser, kettle, smoker, pellet grill, offset etc. because...they like cooking on that equipment, because it is fun, and because they like the food that comes off of it.