I don't think this argues what I posted. If even seasoned mages like Wynne, Ines, Wilhem, Finn, Irving, Rhys, Adrian, etc. can be possessed at any time, why are they ever let out of their towers? I can only see it that either the threat of possession isn't actually that great, or that the usefulness of their abilities outweigh the threat of possession, and if their abilities outweigh threat of possession, all harrowed mages should be allowed to travel unrestricted.
How... black and white. Unfortunately I tend to go by the lore, instead of headcannoning things that support what I want to believe. It's been stated over and over that the threat of possession IS that great, and yes, the more powerful the mage the less likely they are to succumb to possession but that doesn't mean it isn't there.
And yes it was a direct argument to what you wrote, you were saying that mages cease to be dangerous to after they pass their harrowing, I was saying otherwise.
Anders, Orsino, Grace, Quentin and Uldred also tend to disprove your point.