China is also a country that is not friendly to cryptocurrencies, but they are a strategic partner and ally of Russia. So I don't think Russia is using crypto to avoid sanctions and Western countries are being aggressive with crypto because of Russia.
Russia and China are using crypto, including USDT for transactions with one another. This way they avoid sanctions and make payments much faster and more unnoticeably to the outside world.On the official agenda, they may be against cryptocurrencies, but this does not mean that they do not use them for personal gain.
i doubt their government uses the USDT, it would mean a large amount of sending USDT. if it's a known address, those USDT can be frozen. and they find it not in their best interest, remember they are dedollarizing. but the citizens i think in China and Russia could still be using stablecoins including the USDT.
the government of Russia and China do have their own version of SWIFT, they may be using them already if not their CBDC.