Why Are Silver ETFs Like SLV Shorting COMEX Futures?

In a recent interview on CNBC, GoldmanSachs​ Global Head of Commodities Jeff Currie curiously mentioned that: “The shorts are the ETFs. The ETFs buy the physical, they turn around and they sell on the COMEX.” Which is a surprising comment, given that Jeff is apparently authorized to talk on behalf of mega-investment bank Goldman Sachs, one of the SLV silver trust’s authorized participants that can add or redeem 50,000 share baskets. Because if SLV is just a trust, that receives customer money when new shares are added, that JP Morgan reportedly uses to go out and buy metal to deposit in the trust, what exactly is the ETF hedging?