Aircraft gun autosights are not designed to hit slow-moving targets with weird radar characteristics. Also, they are designed to engage targets at ranges on the order of 1000 yards. This balloon may have been flying miles higher than the operational ceiling of that aircraft. I read somewhere that at one time in the past (I'm sorry I can't provide a reference for this) 2000 rounds of cannon fire were unable to bring down a balloon target. That would have been embarrassing, not to mention dangerous! An Advanced Medium Range Air to Air Missile is designed to be fired at fairly long distances from the target, so that's a clue. If anything had gone wrong, no one would have been able to recover it.

This is probably why they chose to wait for the balloon to be out at sea before engaging it. It's not just the balloon debris that posed a danger to people and property on the ground, it was all the ordnance that they might have to throw at it, it has to come down somewhere.

I'm sure the GOP congressmen criticizing the offshore shoot-down of this target are perfectly aware of this, but they are so desperate to blame Biden that they will come up with any lies they can to try and discredit him, to make him look like a fool, or a wimp. (In Republican thinking, the latter is always worse than the former.) Its pretty clear what happened. Biden said, "Shoot it down"; the Generals said, "Wait till its safe." And Biden answered, "Make it so."