The
reason is to get money, the
means is to threaten people with death. Robbing a bank: the goal is to get the money, the robber uses the threat of violence or death to compel the employees to give him money.
I'm not quite sure what point you're arguing; what I was saying that the GP defined terrorism as something that requires a motive of instilling fear; i.e. a goal of the acts that the terrorists is to make people afraid. That's one definition but the INA defines it differently, which is just another definition.
If you define all acts of highjacking as terrorism, you explicitly do away with the requirement of fear. And for good reason, because otherwise one would have to start proving state of mind, which is a legal snake pit.
But if you restrict yourself to people with the intention to cause fear to discern a terrorist, you can't call anyone that hijacks an airplane a terrorist, because your definition requires a different criterion, namely the objective of the highjacking.
To conclude, "it's still safe to call anyone that hijacks an airplane a terrorist." is meaningless because it's said in a vacuum, without a definition of who is a terrorist. This whole discussion is about the distinction between to definitions, and that under one definition some people are terrorists and under another they aren't.
(I'm not taking a position, I don't know and I don't care, definition problems are boring; the fact that the OP failed to recognize this nuance, and effectively turned his argument into a straw man, is what bothers me.)