GG appear some of the most intelligent fish we enjoy the privilege to keep. As you say you'd have no problem rehoming any overgrown fish (do I recall correctly?), you could try growing one out with that in mind.
But overall, the GG is unlikely to be happy long term, as Esox eloquently described, not to mention that territorially and hierarchically aggressive fish become a nightmare in smaller tanks.
Dloks
I love yah, bro, you know it, and I don't wanna lose you from MFK so I'll be honest although it hurts me personally to say this: if you don't become more considerate, I am afraid we will lose you and your much needed here fish expertise and your brilliantly-hilarious presence here on MFK. It will suck. Please, consider changing your ways. Live and let others live... especially if they are not breaking ToS. Pretty please?