Hi! Sweet Goblin control deck. I love goblin tribal, and this is a super unique take on the deck that I really like! It looks pretty dialed in to me, but for the control aspect, it might be worth considering
Zealous Conscripts for the sideboard since it lets you take any permenant and not just creatures. unfortunately he isn't a goblin and 5 is a lot of mana, but being able to
snag Karn, Liberated from a Tron player, or some enchantment slowing you down (like
Ghostly Prison) is a pretty sweet feeling.
Harness by Force or
Traitorous Blood could be good to, since they are strictly better than
Act of Treason (and the double red doesn't matter to you).
Jeering Instigator seems to be exactly what this deck wants, especially since its a goblin itself.
Metalic Mastery seems good for the sideboard in case you're against a lot of Artifacts.
As for Goblin support,
Clickslither is pretty amazing with
Siege-Gang Commander.
I hope you found this helpful! Good luck and Happy Hunting
Oh, and to answer your question. If you gain control of a guy with
Act of Treason, it doesn't get the +2/0 bonus from
Ogre Battledriver for exactly the reason you said. The creature is already on the battlefield so the effect doesn't trigger.