Why does "Market Rebellion" know anything about this? My instinct is that this rumor will turn out to be false. But assuming it's true:
Bitcointalk.org has long been on Russia's block list, so all current Russian users are using VPNs, etc. If Russia bans all non-Russian IP, then that would make it much more difficult for Russian users to access the rest of the Internet, though there's not much that we can do about that. For example, creating a Tor hidden service wouldn't help them at all.
For Russians to access the Internet, they'll have to personally have some non-wired connection to the regular Internet via Starlink, cross-border laser/radio communication, etc., or they'll have to proxy their connection via multi-homed devices which have both one of those non-wired connections as well as a Russian IP. Those latter multi-homed devices could act as Tor bridges or VPNs, but keeping these online for long may become difficult because devices with Russian IPs are presumably located in Russia and can be shut down by Russian authorities once discovered. The architecture of Tor bridges was not set up for this threat model, and probably won't work well long-term.
A more resilient way of bypassing this kind of censorship is a distributed database like
Freenet. These systems function based on an entirely different premise from the normal Internet, so they can't be used to access the normal Internet, but they would allow for more robustly communicating through Russia's firewall. One multi-homed Freenet node could anonymously transfer data from the outside world into Russia, and then this data would be replicated among many Russian-only nodes.
Freenet and similar systems can probably be pretty easily blocked by detecting and blocking all of their traffic, so an even better way of bypassing censorship would be a wireless mesh network combined with a distributed database. I don't know of any well-established software for doing this, though.
In all of the many years I've been admin, I don't think that anything has touched/disturbed me more than knowing that there are many veteran forum members whose countries are currently at war. The Ukrainians are the most victimized, of course, but the Russian people are victims, too: economic cannon fodder in Putin's war.
The Russian section was the first non-English section created (created when Satoshi was the forum's head administrator), and Russians were some of the first adopters of Bitcoin. This war is a tragedy in many more important ways, but it's specifically a tragedy for the Bitcoin community. My greatest hope is that applied cryptography (of which Bitcoin is probably the most successful example) will enable Russians to resist and eventually overthrow their authoritarian government in ways that
give them some chance of continuing their lives. It's not reasonable to expect Russians to resist in ways that lead to almost-certain death or imprisonment.