I expect it to be fixed in a future update. Because I'm sure some players are already exploiting this bug, creating and deleting new characters in loop just to to sell the hero's banner to other players.
To fix the damage already done is another story because while rolling back GTN transaction involved with the Hero's Banner could be easily done, it's not the same story about player to player trades involving more than a direct credit trade.
Bioware could also just decide to delete every Hero's Banner on non-CE accounts. But that would not be really fair to the innocent buyers.
Or they could replace every Hero's Banner on non-Ce accounts with a Republic or Empire banner. That would be more acceptable I guess.
Or they simply gonna do nothing about it and say that is how the item is supposed to be in the first place