"However, I personally disagree with the QF policy regarding domestic J class ticketholders' lounge access. For example, one of the managers in our company whose in-charge Asia-Pacific region comes over to Australia once a year, and he normally takes two or three domestic flights which the company always gets a business class ticket for him, but he has been denied for access of the domestic QC lounges"

Why don't you include the domestic flights in as part of his international itinery? If you do this then he would be entitled to lounge access since you are entitled to lounge access when travelling domestically as part of an international itinery.

It is only purely domestic itineries where the lounge access restriction applies.

Dave