The SEC's point is that it is already illegal today, and only the most egregious ones (e.g. Trendon Shavers, Charlie Shrem, Alexander Vinnik) will be criminally prosecuted.
I think the problem is less SEC and more money laundering. Something tells me not a lot of KYC is going on.. My guess is that any money laundering that causes grief for the US (ie, terrorism) will get people arrested and put in jail for a long time.
It's not illegal today, but it will be soon enough, and when you piss off powerful people they find a way to shut you down, one way or another.