Instead of "rather than," it can be both. Was the release of the hostages contingent on receipt of the funds? If yes, then it's ransom. It doesn't matter if we owed them the money or not - an issue that has been under dispute for decades.I think that the important intent is the intent of the person doing the act, in this case paying the money. Only the person who does something knows why he/she did it.
More generally, the underlying problem, as I see it, is that it is not in the best interest of the American people for crazy people in the world to think that we pay ransoms for kidnapped Americans. So, why would I want crazy people to think that? Answer: I don't.
You have to look at both players. If the release is contingent on the money changing hands, then the way I see it, it is ransom. Do you say is is not ransom, if the kidnapping was undertaken in order to encourage an old debt to be settled?