A time-honored tradition.
You make a good case for no trades, and a good case can be made the other way, too. The US, though, routinely trades for or buys hostages. Reagan did it, Kennedy did it, Israel does it, even while proclaiming it's not an option.
It seems to me it should be done on a case-by-case basis. Sometimes it would be worth it, sometimes not.
If that kid was a deserter I can't understand getting him back. Unless the US is simply unloading 5 low-level incompetents on them, in exchange for 1 low-level incompetent.