Is that the law, or the ATO's interpretation of the law? At times the two can be diametrically opposed.
GST status of bullion coins is not about exemption, it merely explains how metal is categorised, saying that numismatics are Taxable (10%), bullion coins are Input Taxed (0%) and newly mined refined metal is GST Free (0%). You cannot "extend" this to imply CGT exemption. What is important about the GST ruling is the reasons given for the different GST treatment of precious metal coins (coins being a generic term). These reasons (coin is traded primarily on spot price, small premium, no rarity etc) are likely to be applied by the ATO to clarify what "coin" means in respect of http://www.ato.gov.au/corporate/content.asp?doc=/content/00208572.htm&page=12#P310_29582 I consider it risky to assume that "coin" means bullion with respect of CGT exemptions.
