Behavior is public. It's what each person projects, often unknowingly, to everyone in the vicinity about their thoughts and feelings. Even a professional actor would have difficulty projecting the correct behavior if said actor were plotting a very real suicide bombing. That would take either years of training, or the correct dosage of drugs. Observing behavior is passive.
Scanning and patdowns are active. The TSA personnel are invading the private space of the person being examined. An examination is active and intrusive. This is the reason many people find it a violation.
And they are correct. It IS a violation. Going from passive to active makes the assumption that the people being examined are guilty of some crime. It is "Guilty until proven Innocent" and it is completely contrary to American values.
It is also easy to bypass, as small or private airports are not subject to TSA scrutiny. A criminal could load up a small plane with, say, explosives or biological agents and take off from a tiny airfield outside of TSA jurisdiction and then fly it into whatever. And this could happen at a dozen locations for maximum saturation. And it completely bypasses the "security" of the big airports. Hell, he could drop chemical agents via a crop duster onto a busy highway during rush hour, and no one at the TSA would be the wiser until it's too late.
So, this increased "security" is nothing more than a set-up engineered to get the public used to being scrutinized by their government.
As for blaming Republicans or Democrats for X issue, each group is simply there to ensure that their party gets as many members into office as possible. This generates revenue for their party and their members. Political and social ideas are secondary to that objective, anymore. Each side has performed the same actions that they vilify the other for, often just before, after, or during the same "objectionable" action.