He couldn't. The coin was doubled-sided remember ? Edgar wanted to sacrifice his freedom because he loved his brother and he wanted to give freedom to him instead of to him.

But I picture them living somewhere a poorer and far away from the Empire and just trying to live a normal life. Sabin wouldn't have his muscles and Edgar would be less of a flirt because I really believe that the reason why Edgar was so flirty was because of escapism and boredom.