Well since you bring up the Blades of the Fallen Prince...
"You believe that you are in control, that your will is your own. Yet you do as He commands. You exist by His whim alone. You imagine yourself to be free, but you will always be His instrument..."
Oh! Or the new "Empty inside. Just like me." while you slaughter Azeroth's defenders at his command. When Fire Mages go to get Felo'melorn, he acknowledges that he knows they want it to fight the Legion, but he has no intention of helping.
Whatever Bolvar was when he went in, in the last few years on ice he has become a very Not Nice Man. And for a guy who supposedly wants to use the Scourge "in Azeroth's defense," it's a bit fishy that so far he's had you fight the Silver Hand, the Thorignir, and the Red Dragonflight, but not strike any real blows against the Legion at all.
In short: Dude's evil, yo.