If you are not a stupid person you realize that is not how Due Process works.
If i accuse you, FastLane, tomorrow saying 'I saw you wade across the Rio Grande and we should deport you instantly', it is only because you are granted 'due process' you can prove i am lying and not be deported.
If you say all the government has to do is say the words 'they entered illegally' and the gov't does not have to give them any chance to prove otherwise (no due process) then that accusation can be used against anyone including US citizens.
You have to believe government is perfect and NEVER makes mistakes so say no person should be able to defend against a gov't claim of 'X' and that claim of 'X', allows the gov't to act without any due process of defense against that action.