I wouldn't put it past them. The only country to worry about in "BRICS" would be China. India's economy is not yet large enough and they're more democratized than the CCP. China's looking to form dependence on Yuan by other countries -- does it seem so wildly speculative that China predicts Bitcoin to be a future threat? Do not think short term -- think 10-20 years down the line. Could there reasonably be a world in which countries use decentralized currencies to conduct bilateral trades/transactions that would cause China some concern if their long term goal is Yuan dependence onto other countries?
I feel like whatever nations can do, they are allowed to it, not like anyone forces them to do anything. Lets assume that China is spending money and time on making other nations depend on them, if other nations don't fall for it, they can avoid it, but if other nations end up accepting that, then there is nothing we can do about it.
For example, China is spending tens of billions of dollars to build amazing infrastructures, literally making the nation from scratch, its airports, roads, hospitals and so much more and in return they only want one thing; trade them using yuan and nothing else. They don't even meddle with us spending dollar in trading with others, they only want us to trade using yuan with them, if more then that's great but the only requirement is them.
Is that a trick to make us depend on them? Surely, but they are at least giving something in return too, so far we have used dollars with everyone and USA offered absolutely nothing for it, so this is at least better.