Let it happen.
It will certainly prove Trump's claim that three to five million illegals voted for Hillary is a lie.
It will almost certainly prove there is no significant problem, whether or not involving illegals.
Unless they fear some giant propaganda fraud as brazen, damaging, and egregious as the initial, totally baseless claim that all of Hillary's lead and more is made of 3 to 5 million fraudulent votes cast by illegal aliens.
Gives one pause.