It wouldn't matter. The government presiding has no way of knowing where that plane is heading. Are the hijackers taking it to a different state? Are they targeting official buildings? Are they flying till they hit a large populated area? Are they taking it to a nuclear power plant? You don't have any way of knowing.

That's a really big gamble to take. Could hijackers just run the plane into the ground somewhere? Yeah absolutely. But they could also target any number of other things. And unfortunately that means you have to make the choice with the fewest possible casualties. Which unfortunately means that taking out the plane is the safest way to ensure there's no bigger attack planned.