He wasn't fit to rule over anything more important than a 12 course meal
I broke a sacred oath and stabbed my king in the back. I killed my own cousin. When the gods judged my brother guilty, I helped him escape their justice
Threaten? As in "I'm going to open your lord from balls to brains and see what Starks are made of"?
You have proof? Or do you want to trade gossip like couple of fishwives?