But doesn't proving that the person has lied also require additional efforts, and if that person will contest the desicion in court, can become a long process?
I would argue that proving somebody lied on an application would be easier than proving something like “this person is a danger to the US”. The 2nd is much subjective.
To prove that he lied on the application form, they would have to legally prove him as a terrorist. The legal process of proving someone is a terrorist would be same. So isn't it pointless?