Surprising discovery
Until recently, I always thought the I-League were basically a glorified "pop-up" minor race along the lines of the Vegans. I know in GalCiv 1, they were much more interesting, but I had assumed that was one of the things lost with the nerfage of minors in GalCiv 2.
Then I fired up a game of TOA and saw this:

This was one of three different Iconian systems that defected to the I-League over a short period of time. It didn't happen to anyone else, which leads me to suspect that this "defection" process works best on civilizations that are doing badly - I never met the Iconians, but all indications were that they were at the bottom of the galactic pecking order, and they surrendered just before I quit. Possibly the I-League's ability to do this was reactivated for TOA, or possibly it was always present but the conditions were never right. I'm not sure.
At any rate, it's great to know that I can still be surprised by this game after all this time.