Real question: why they just did not register their company in countries like Switzerland and operated from there?
1) Registering a company in Switzerland requires a Swiss address and Swiss national as a director. See https://www.companyformationswitzerland.com/register-swiss-c... and elsewhere
2) Registering a Swiss company wouldn't by itself allow them to escape US DoJ enfoncement actions. see https://www.justice.gov/opa/pr/ubs-enters-deferred-prosecuti... for example
3) Registering a Swiss company wouldn't exempt them from KYC requirements http://bankersacademy.com/pdf-aml/amlswitzerland-law.pdf for example says that the swiss AML legislation includes non-bank financial institutions (such as exchanges)
Edit to add: It's also non-trivial to get a Swiss work visa if you're not a national. I had one for a while and it required a Swiss company to use up one of their finite central allocation and show that the work wasn't replacing the job of a Swiss national and was being paid the average wage or more (this to prevent exploitation of migrant labour apparently).
If you just want to work, maybe. If you want to found a company and have half a million CHF of capital, it's a different story.
The other statements still apply.