The article clearly doesn't go into the process beyond what's on surface. When I participated both the manager and the employee wrote an initial document that would be shared with each other. These documents are the basis for the presentation. The employee had time to go through the manager's document and rebut each of the points their turn (as did the manager), so it seems slightly disingenuous to suggest that neither party has access to the other's claims.
During each parties presentation, they would go through the document and bring in supplemental evidence (which the other doesn't have access to).
The format I went in was: Employee presents their document -> Employee rebuts manager's document / Q&A -> Manager presents their document -> Manager rebuts other presentation / Q&A
The panel then has the option to bring back the employee for additional questions.
I'd be interested if/how the ordering of the presentations affected the panel.