Okay lets change some history.
The Betrayer: Perturabo
Now lets see who follows
Emperorís Children = Loyal
White Scars = Traitors (Tzeentch)
Space Wolves = Traitors (Undivided)
Blood Angels = Traitors (Nurgle)
World Eaters = Loyal
Ultramarines = Traitors (Slaanesh)
Thousand Sons = Loyal
Word Bearers = Loyal
Raven Guard = Traitors (Undivided)
Dark Angels = Loyal
Iron Warriors = Traitor (Automatic)
Sons of Horus = Loyal
Night Lords = Loyal
Iron Hands = Traitor (Khorne)
Death Guard = Traitor (Undivided)
Imperial Fists = Loyal
Salamanders = Traitor (Undivided)
Alpha Legion = Loyal
Wow. Only the Death Guard and Iron Warriors remained traitors this time.
I would also like to point out that Fulgrim is currently never going to be the Warmaster, because the lowest score on 4D6 is 4.