I have seen the same issue before. According to a leading lawyer he can be on the committee as the act was meant for external building managers. The issue is if he is not a registered company, he would be considered as an employee of the strata plan. In the sense of superannuation and PAYG is concerned and is a PCBU and additionally needs to comply with the WH&S and that to terminate the relationship it is subject to the same employment law relationship you would need to deal with in your business.