This sounds like a bunch of baloney for a few reasons:

1) The US government is concerned with those services that convert to and from the US Dollar. In order to convert to the Dollar, an exchange must become compliant with federal "money transmitting services" regulations.

2) Bittrex doesn't convert to and from any fiat currency (including the US Dollar). For that reason, the US federal government isn't concerned with what Bittrex does. As far as the US government is concerned, Bittrex is engaged in converting one "useless" (ie., fiat-less) token for another.

3) There is one exception to this rule: If a government (including but not limited to the United States) thought that a website/business/entity was involved in other kinds of illegal activity — like financing drugs or weapons, or promoting child prostitution, and so on — then that government might inject itself into its proceedings. However if that government's fiat currency wasn't involved, then the criminal charge would pertain to the illegal activity itself and have little to do with any fiat-less tokens being exchanged.

I think the more important question here is this: Why did the original poster go to all the trouble of creating this remarkable FUD about Bittrex today???