The same attitude gave us WWII. Russian delivery systems are mostly old junk, weapons were not maintained, so fissile material is mostly depleted, making them just dirty bombs. Adding the above together gives Russians a bunch of failed launches and contamination of their own land. Of course, we need to account for their epic stupidity and propensity to disregard human lives, including their own. We need to deal with just the bottom line: a sizable bunch of Neanderthals ready to die for their Mordor. I say let ‘em.
Russians are down to 142 million people today, with an Army under 300,000, they have no intention of going out in a nuclear blaze of glory.