I think you're stretching way too far in rationalizing your position.
"On the alert for suspicious vehicles"? "I'd guess that Ryder trucks get a pretty good once over if they are spotted on the streets whether they are spotted by common citizens or by LEO's, on the other hand no suspicious eyes are able to scope out an inbound aircraft"? It's not too hard to make a vehicle look "not suspicious". And, a truck doesn't have to say Ryder on the side, nor does it need to have a neon sign saying "terrorist" in order to be dangerous. A stolen van will do quite nicely. Trucks don't exactly stand out in a city, you know.
As far as avenues with which to stop an errant vehicle, the advantage of using a vehicle for an attack is that this doesn't even become a concern - a vehicle would never be recognized as "errant" in the first place.
The overreaction is ridiculous, period. ANY airliner that flies into the area is "less than 3 minutes away from the white house", because a friggin 150 is much, much slower. The press are proven idiots, and the ignorance of those in the goverment is astounding.
I still think the pilot should have been shot down, because I'd rather see him get smoked than my rights violated further in the latest "War on <enter name of evil thing here>".