The story behind this skin was recently explained on the PlayStation Blog by Apsyr's director of Product Chris Bashaar. In brief, there was a low-resolution message in the game written in Aurebesh - "Cash in all bounties to play as Boba". Even if you did this, there was no unlock at the end.
Now the team has "brought this easter egg to life", and when you complete the campaign you'll be able to equip a "new Boba Fett skin for the next playthrough". You can learn more about Star Wars: Bounty Hunter in the original announcement.
