I know i don´t have much say in this, but I feel it´s a bit farfetched. Spy for Varian Wrynn, killed off a massive group of scourge, escaped the Lich King...
Also has been undead for 2 years. The Lich King turned him into one of his scourge, which means he would have been undead then.. The Forsaken are free-willed for quite a few years now (5+). So this doesn´t add up.