Quote: I think there is an unwritten code - or at least I will think that until someone points to a written rule
This is what people are querying. What evidence do you have that there is an unwritten code or agenda?, or why are you asking the question? If most people say they have never been barred from entering a harbour or port when a storm is arriving or has arrived, the only real difficulty is whether it is actually safe to enter in the conditions at them time.