The type of Russian that would flee are the type that would get shot for retreating so the only thing you're costing them is ammo.

At this point, most Russians KNOW the world is against them and know that living outside of Russia, unless they prostrate themselves like in North Korea only this time saying how evil Putin is they'll get targeted, their belongings seized and even lose their livelihoods. And since you want them living on their knees, wouldn't be surprised if most Russians go "fuck it, when are we turning Kiev into a parking lot?"