>Ex post facto criminal laws are barred by the constitution for good reason.
I think your analysis is flawed. They didn't come up with some new law and apply it to these people ex post facto. These accounts were contributing to the money laundering (per accusations, albeit indirectly).
Another way to look at it: if these people were contributing knowingly to a project that was laundering money, should they be punished? Of course.
This is a anonymous token. It can be used for a plethora of things, including earning passive income. If we apply this line of thinking, everyone who has ever contributed to Monero and Tor should be punished because both are widely used for criminal activity.
I think your analysis is flawed. They didn't come up with some new law and apply it to these people ex post facto. These accounts were contributing to the money laundering (per accusations, albeit indirectly).
Another way to look at it: if these people were contributing knowingly to a project that was laundering money, should they be punished? Of course.