Meanwhile announced the same week:
German prosecutors have abandoned their criminal investigation into staff at Deutsche Bank suspected of helping launder dirty money from Russia and neighboring countries through the tiny Estonian branch of Denmark’s largest lender, Danske Bank. The bank washed $230 billion in likely dirty money into and out of accounts that were controlled, through anonymous shell companies, by thousands of secretive figures in Russian and other former Soviet republics and satellite states.
I wonder where will this Larry guy from rural Ohio find $60M to pay the ransom to Fincen. He didn't do anything evil or nefarious in my opinion. His biggest problem wasn't that he created a website/script that tumbles crypto (there are many others), the problem was he likely was quite good at it and promoted and targeted his site to darknet markets.
As was already mentioned by OP in the first post, there are some Bitcoin wallets which now have tumblers built-in into them, so no need to use a custody tumbler, use something open-source, fully decentralized, created by someone anonymous. I don't understand OP's question "will it apply to non-custodial mixers?" Who is Fincen going to fine in that case? The drug dealer? The Chinese dissident? Or perhaps the C# programming language?
And even if he actually has the money (no idea, maybe he has...) the bad thing is this was only the administrative part of the process and simultaneously criminal part is happening and can end up in jail time.
Check out Fincen's mission:
"promote national security through the collection, analysis, and dissemination of financial intelligence and strategic use". It reminded me of the motto
"To Protect and to Serve" of Los Angeles police that was later adopted by many other local police forces. Role of police isn't to protect you or to serve you; role of police is to protect themselves first of all, to serve their superiors, then the state. If after doing all that, they have some time left, perhaps they will protect you by stopping your car and asking weird questions. It is the same story with Fincen, national security was enforced on this day.