Wow! That RTGG is gorgeous! I hope I never see one that nice for sale, 'cuz I'll probably do something stupid...
I've only had one GG, a standard grey one, had it for years and it was just about the perfect large community fish. It never started a fight with anything except others of its species (which it absolutely would not tolerate), it never got picked on by other species, and it could be kept with even the smallest of fish without paying them any attention whatsoever. I know they aren't all that way; I hope yours grows into a calm one, as it will make a spectacular centerpiece for that tank with all its smaller tankmates.
Personally, if that were my fish and anything else caused that guy any stress or raised a ruckus, I'd throw the troublemaker out immediately.

Let's face it: a Gold Sev is just another dime-a-dozen cichlid...