How to thwart TSA "security"

A couple of weeks ago, the TSA found a plastic dagger via it's virtual strip-search machines. In the picture, the dagger appears to have a four-inch blade. In the comments, several people (rightfully) take TSA to task for this find, as it is not a threat to aviation. Our point is that it is not worth the liberties and the money to find something so insignificant, but some anonymous person seemed to want an answer as to why we were not focusing on the intent of the person trying to smuggle it on. My reply exposes several "weaknesses" in TSA security, so I doubt it will get approved. But here is my basic reply (I did not save a local copy, so I don't have it word-for-word:

The intent of the person carrying this dagger is irrelevant, as it is not a threat to aviation. If he had ill intent, here are some other ways to get past security:

First, make the checkpoint itself the target. I'm not sure how much damage you could do with a 4" plastic blade, but you'd be just as big a threat to aviation there as if you managed to get it on the plane, what with hardened cockpit doors and passenger awareness and all.

Second, place the blade in the scanner's blind spot. See point one as to why, even if successful, you're still not a threat to aviation.

Third, take a pair of scissors, which are allowed, instead. Once past security, separate the blades. Now you have TWO weapons instead of one. See point one as to why this does not matter, though, and why I suspect the scissors are allowed to begin with.

Fourth, go through security and find a place inside the "secure" area to have a nice steak dinner before your flight. Pocket the steak knife before you leave the restaurant. You're still not a threat to aviation, but at least you had a nice meal before the other passengers on the flight took you down when you started trying to take over the plane with a steak knife.

Finally, fly first-class and opt for the in-flight meal. Then you can wait, in the comfort of first class, for a flight attendant to hand you a knife. Again, at least you had a nice meal (with the bonus of a comfortable seat on the plane) before the other passengers took you down.