Can anyone explain what TFR's are supposed to do?

In article ,
It was explained to me as follows: those responsible for security assess
all possible threats and create plans to mitigate each one. Regardless of
our opinions, small planes are indeed a threat and the easy thing to do was
to restrict their activity within a certain distance. They are considered a
greater threat than large commercial planes (to the mobile president) for
reasons I will not go into here. GA is an easy target for restrictions
because of GA's limited political and financial clout and the extreme ease
of clearing the area of GA aircraft.

There has been one act, a terrible act, of terrorism using planes.
They were not that small. Anything and everything is a risk. But having
small planes fly within a 30nm radius is far far far less of a risk than
having the president in a open crowd with several thousand people.
It's a political not a logically policy. I can understand (even accept
that). I think myself and others would just like some honesty on this
point.

Claiming that a truck bomb or suicide bomber can be a larger threat is
besides the point. Each separate threat has a plan to deal with it. GA is
dealt with by TFRs. Other threats are dealt with in other ways.

I understand the theory...