See Fair Work Act 2009 s.387(d)
There is no positive obligation on an employer to offer an employee the opportunity to have a support person:
This factor will only be a relevant consideration when an employee asks to have a support person present in a discussion relating to dismissal and the employer unreasonably refuses. It does not impose a positive obligation on employers to offer an employee the opportunity to have a support person present when they are considering dismissing them.
A support person does not act as an advocate – a support person does not present or defend a case on behalf of the employee.
 Explanatory Memorandum to Fair Work Bill 2008 at para. 1542.