The SEC used that as an excuse to deny all previous submissions <even though Gold and Silver prices are being manipulated globally by syndicates> I think it is OK for them, if they can identify these syndicates with their surveillance software on their platforms or to hide their actions.
It also comes down to accountability. It's known to regulators who the manipulators are of precious metals, because most of the paper demand is generated within the US, and within regulated platforms, unlike Bitcoin which is largely driven by Asian exchanges the SEC can't do much about.
I'm certain that with Bakkt and the Nasdaq going live and generate decent enough volumes, it's more likely than ever before to see the SEC approve an ETF, especially if CME's volumes continue to grow on top of that. CME traded 91,000BTC in a single day last week, which is insane. Real dollars being traded here, no empty Tethers.