You're correct. But as a temporary measure to stop people dumping Rubles, offering gold as an incentive is clever. As you say, whether that makes sense longer term is questionable.

Being cut off from a financial system that's actively internationalist and opposed to you isn't a negative if you're ultranationalist and have already accepted that those goods have too many strings attached.

It's a game of chicken, and honestly Russia can turn off the oil & gas pipelines next winter if they're still being locked out of the international marketplace. Germany will cry uncle faster than Russia goes bankrupt. Any move that gets them closer to that point, short term, is a win for them.