No, because there have been attempts that the scanners have not caught, and were thwarted not by the TSA, nor any government agency, but by other passengers. Know thy history, I'm not even accounting for the white-hat tests that the TSA has soundly failed.
http://www.washingtontimes.com/news/2013/mar/8/tsa-fails-und...
http://blog.tsa.gov/2010/12/70-detection-failure-rate-being....
http://www.prisonplanet.com/tsa-scanners-repeatedly-fail-to-...
In this case, by criticizing the spending of scanners as a deterrent to potential plots, are we not playing the part of CEO who complains about a small security expense as opposed to waiting until after a disaster to respond?
When the cost of security exceeds the cost of what's being protected, the solution need be reconsidered.
Similarly, the nude scanners would have done very little to stop the 9/11 hijackers, whose weapons were simple and equivalent weapons could be improvised from items that anyone can find on the other side of a checkpoint. Whatever we were doing in August 2001 to stop less-determined attacks was working back then and would work equally well today. The simplest conclusion is that whatever else is being done to stop a 9/11-style attack is working, and that the checkpoints are just a distraction.
Not that we should be surprised by that. The TSA was going to allow people to carry small knives through the checkpoints, and noted that you are already allowed to carry far more dangerous items through -- except for box cutters, because of their appearance. Then there was an outcry from people who are terrified of knives being on airplanes, and so the policy change never happened. With that kind of logic, it is a stretch to say that the checkpoints are keeping us safe.
Besides, the point about alternatives is problematic in other ways. If vast public resources are expended moving problems from one location to another location, were those resources well spent?
Not when all the materials one needs to construct a dangerous weapon are available on the other side of the checkpoint. Go to the duty-free shop and buy a glass bottle, and now you are ready to make a shiv.
For that matter, you have lots of sharp metal things and dangerous chemicals in your laptop, and you can walk through security with that.
I doubt the 9/11 hijackers would be deterred by the nude scanners. Sure, you would stop them from bringing a box cutter through (maybe), but there are a dozen other weapons they could have carried through or procured past the checkpoint. The nude scanners might catch someone who is trying to sneak a gun through security, but so do metal detectors -- and metal detectors might even do a better job.
About as effectively as arguing a tiger-repellant rock is strong deterrent.