BRIC(S) is a Goldman-Sachs white paper, turned PR initiative.
It's not common market, much less anything resembling a security architecture.
Don't get me wrong, I think a Global South alliance or economic union/federation would be an amazing advancement for EVERY worker in the world, not just those outside the first world.
Unfortunately, BRICS isn't that, and can never be that. But maybe, if we're lucky, it can be the League of Nations style doomed prototype for a more successful and effective organization to be born out of its ashes. Though, ideally without requiring another world war.