My main's backstory was actually a perfect fit for this. Attracted by more affordable rent than Providence, Safehouse moved to Paragon City from NYC when he began studying at Brown University. Having been a small time hero in NYC, he was hoping to make more of a name for himself since he no longer was competing with the "big time names" like Spider-Man. It kind of worked - student by day, hero by night. He became a famed hero in Paragon over the years. When he graduated from Brown, he decided to stay, studying for his Master's at the college in Steel Canyon.
The way I see it, Safehouse began to disagree more and more with the FBSA, the way it did things, and how it ran its heroes (not intended as a statement on CoH itself, but just kind of how I see SH doing things). When a mission gone wrong resulted in the death of his best friend, Safehouse had had enough. In a terrible depression, with the darkness threatening to take him, he left Paragon City to be with his family in New York. Now, he is in retirement.
If the game were to come back, or if there were a CoH2, or if/when CoT takes off, they will have begged and pressed Safehouse to come out of retirement. He would have been convinced that the time was right for him to stop wallowing and begin fighting for righteousness again.