Which is probably why he is being kept around - to unwittingly out the scumbags. But honestly, pretty much anyone associated with the Obama admin is an America-hating scumbag, so it can't be that difficult to pick these people out - the Left only hires fellow travelers, so just look at who hired the holdovers. And of course, connections to Soros are a big red flag, so McMaster is a major fail on most counts.
And McCain is the one that pushed McMaster for his position.