His argument bases on the presumption that the counterfeit and the real thing are very close in quality as to be indistinguishable. You can sell the real item and keep wearing the counterfeit and nobody is any wiser, or vice versa. Whether you keep the "real" item to wear or wear a counterfeit is inconsequential. The real value of the item passes along with the NFT to the new owner. The remaining item whether is real or not has vastly less value.

The economic incentive of counterfeiting is ruining in that the counterfeiter cannot sell 1000 counterfeits with the full price as the real item.