If Russia disconnects itself from the internet then I think they'll face a lot of negative consequences (not only with bitcoin but with engineering and other advancements too).
I wish President Putin is here or has some representatives from his cabinet who can read and tell him all this for him to reconsider his decision. His action will hurt more people than he thinks he will gain. It is the same way the US and their allies should read too. The boycott of the internet in Russia can come from either Putin or the EU as sanction. Time will tell. This war is not only affecting Ukraine, it is also hitting the Russians harshly too. Innocent souls are being massacred in both countries.