The bolded part is what made his operation illegal. Mixers otherwise don't need to be warned of anything. I'm not sure why some people seem to have a vendetta against mixers when they exist to help them preserve their anonymity. At the end of the day, mixers are just tools and are only as good as their users.
If anyone decides to get legal that won't wash. They are handling the money of others and moving it elsewhere with a polish of untraceability. Because of that they should be vetting the source of the money and vetting the people who sent and received it. It's just about the perfect definition of a money laundering operation. I think centralised options are on borrowed time unless they bury themselves deeply.