Hillary Clinton is a war-monger. Words have consequences. She is reckless in speaking off the cuff about foreign leaders, particularly important ones like Putin. She could learn a thing or two from Donald Trump about treating foreign leaders like Putin with some respect. Hillary flying off the handle will drag us into a world war. (And she is a hypocrite.)
Therefore, the Kremlin's concern is legitimate for that reason alone.
Putin may be a thug and a nationalist, but he doesn't run in Islamist circles and thinks western civilization would be worth preserving. Bottom line is that I'd trust him a lot further than I would Hillary.