I see this as a perfectly normal step of one Government. You need to have legal background to fight against fraudulent activities and money laundering, while on the other side, you cannot allow these asset to interfere into your monetary system without control.
The easiest way is to prohibit everything new. This is done in all states where the rights of citizens are not respected. Russia, unfortunately, belongs to such states. Moreover, it is interesting that the Russian government does not deny the novelty and advantages of cryptocurrency in relation to conventional currency. It helps other states implement their digitized currencies, such as Venezuela. However, they decided to ban their use for their citizens.
Civilized states fight against money laundering and other abuses using cryptocurrency by regulating their circulation, rather than completely banning them.