There is already a regulated market - the Winklevoss' Gemini exchange. They went out of their way to make sure everything about their exchange is in compliance, specifically for it to serve as the market for the ETF commodity.
Unfortunately for them, the SEC, quite reasonably, requires more than one regulated market to exist for the underlying commodity, and probably preferably not owned by the company behind the ETF itself. Seems obvious in retrospect.
> Unfortunately for them, the SEC, quite reasonably, requires more than one regulated market to exist for the underlying commodity
From the ruling, it doesn't really seem that was an issue. That Gemini does very little of the US and an utterly miniscule amount ogmthr global bitcoin trade made the surveillance agreement with Gemini insufficient, but a single-but-dominant regulated exchange would probably be sufficient.