The point is intimidation. If anyone can be renditioned without legal cause and with no hope of redress, who the hell is going to criticise Trump?
They definitely have the attitude that they should be able to do what ever they want, if they call it "For the good of our country". That excuse and "In the name of God" has been the two leading justifications for inhumane acts for thousands of years. Though their actual reasons are usually quite different.