He does provide examples here, and numerous times elsewhere, of claims which turned out to be entirely false. This has happened in the past, in Iraq with the WMD lies, and Vietnam with the Gulf of Tonkin. This is a big problem.
I'm not convinced of your smear against Greenwald as a pro-Russia journalist. As an openly gay man he would have a lot of difficulty there. And Jews have been fleeing Russia. As far as I can tell, his biggest bias to protect minorities like himself, so it would be exceptionally odd for him to be pro-Russia. There is certainly no evidence I have ever seen of that.
Anyways, before this election, if someone told me that Russia, China, Iran, etc, were all trying to influence US politics, hack US gov/bus, etc, I would say that is a given. Everyone knows that. There is a reason for the Russian fear mongering and not Chinese fear mongering, Saudi Arabian fear mongering, etc.