The Russian power structure has never been legitimate as Aristotle would define power.
An argument about whether Putin is legitimate in Russia would go little to no where. The reason is most people say he was elected it is what it is. Aristotle brushes that aside for the bigger picture creating political theory. Putin is just a thug there is nothing else there.
There is no enigma. There never has been any legitimacy to any Russian government.
Put another way before or after Putin is put into this question of mine would you see Putin as legitimate as he is the result of their power structure. The question, would you want to see the Russian form of government in your own country governing you? Now picture Putin at the top of that government and answer the question a second time.
Either way you would repudiate such a decision as a complete heck no.