defining cryptocurrency in the law may actually grant it some legitimacy.
We do have a law related to purchasers of stolen goods/properties in good faith but the thing here is even the unknowing buyer/seller receiving the stolen goods (crypto in this case) doesn't have any direct links to the crime but he has the legal obligation to return the funds back provided that his money or the item he exchange for it will be returned. In what the Russian government is trying to propose they will just instantly confiscate the cryptocurrency without even returning anything to the unaware party. This part is where the Russian citizens are in a bad position since really they don't have any kind of protection once their money is confiscated by their own government.
that's how it works in the USA. the police can seize any property by claiming it has been involved in criminal activity. the property owner doesn't need to be found guilty of a crime; the police can simply take his property. fighting to recover the property is extremely burdensome and the success rate is low, so most people don't bother.
https://www.heritage.org/research/reports/2014/03/civil-asset-forfeiture-7-things-you-should-know
i assumed that russia was no different but perhaps i'm wrong about that.