My friend needed some change, so I traded him two $10 for a $20. Then I gave that $20 bill to Domino's and they gave me a pizza.
Let's do the math here. $10 + $10 + $20. Well dang, that pizza cost me $40.
What if instead of eating the Pizza yourself you shipped it to a friend in Seattle?.
That explains why you no longer have neither the money nor the pizza, or in this case Leafs organization has neither
Hallander nor 7th round pick nor Jared McCann.
This is not hard to prove as Hallander and Leafs 7th round pick belong to Pittsburgh and McCann now belongs to Seattle and Toronto has nothing left from that combined transaction.
You seem to be arguing the price to protect Kerfoot a player you already owned is not doubled by your analogy, but nobody is really saying that. However if you simply let Kerfoot go to expansion, you would still have Hallander and pick today & $3.5 mil recaptured cap space to go out and get a player via free agency to replace him and then had all 3 assets in Leafs organization still at the expense of only Kerfoot. Or you would still have Hallander and pick, to use as tradable assets toward a replacement player to use post expansion draft, but for your own roster, not another teams.
Maybe Leafs fans would feel better to define the losses of 3 assets (prospect, pick and roster player) as the protection cost to keep Kerfoot.
PS. Yeah but every team needed to lose a player to expansion, true. But Leafs needed to spend a prospect and pick to obtain that player
first, that they then lost to expansion also. They couldn't send just the pick and prospect to Seattle directly to get them not to take Kerfoot, because then they would still have lost another roster player like Travis Dermott
in addition to the other assets via expansion. Then nobody would be arguing they lost either Hallander & pick
or Dermott but not all 3 to keep Kerfoot.