That would have to be one big a** angelfish. Rummynose tetras get fairly large when they are mature. Many people that keep discus also stock their tank with rummynose as they are a good indicator for water quality. Their noses will be bright red when the water quality is good. I would say that angelfish with rummynose will be just fine but I would add the rummynose first because if the angelfish are put in the tank first it becomes their tank and don't take to new guests to kindly.
I have kept Rummynose with somewhat large (?) adult angels in the past--angels with bodies about the size of a dollar coin?. No problems at all--rummynose can actually get pretty big and they are very fast swimmers. I have never seen any aggression from Rummynose towards anything.
IMO, Angels and Rummynose should be fine. I agree that the Rummynose should ideally be in the tank first, though. Unless you have a tiny angel, and are hoping to raise it to maturity.