The naturalized American citizen grew up in Azerbaijan under Russian rule and lived under it most of his life. So he kind of knows about Russian tyranny, too
He knows a great deal more than does the current administration, including the President, about the current Russian dictator, Vladimir Putin. One of the things he knows is that when one validates a man who interferes with our elections, enables genocide in Syria, and invades neighboring nations, one becomes his accomplice.
Another is that when there are good reasons to wonder whether your own national administration is foolishly sharing information with that regime- whether through intentional collusion or through simple naivete and negligence- the real question isn't necessarily whether laws are being broken. The real question is whether the President's oath of office to faithfully discharge his duties and to "preserve, protect and defend" the Constitution is being broken.
In short, he knows a great deal more than many of his fellow Americans inside and outside that administration seem to know.
Angela Merkel seems to know it, too.
Photo copyright 2007, S.M.S.I., Inc. – Owen Williams, The Kasparov Agency (http://www.kasparovagent.com/photo_gallery.php) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons