How do you have a proper audit? It's impossible to know that one side won't try to sway it in one direction or the other. That's the nature of the voting system - it's volatile and prone human intervention. That's why you need at least two sides checking each other, ensuring that the other side is honest. That's also why the audit was called in the first place - because one side was barred from observing the other as the counting was taking place.

As for how secure the audit is? Way more secure than November, that's for sure. This one has live feed being displayed to the public. Better than when the D's were literally taping stuff to the wall so people couldn't see, or how when observers who are legally allowed to observe as per election law were only allowed to view the counting with a pair of binoculars.