For those having trouble turning blue, I saved the game, exited out of CBE, and then later came back and reloaded, and it happened in 2 turns.
I watched MadDjinn's ARC preview, and he got it in like ~60, IIRC, which is way more than mine took. And I killed less than he did.
A strategy for how to expand with green aliens: get one level of Purity, which gives explorers immunity from attacks. Then have explorers escort your settler/workers around, and they'll be safe. The explorers can even take nests and they won't be attacked. This benefit really belongs in Harmony tree, not Purity.
In order to make friendly aliens worthwhile, they really need to get rid of zone of control, above all, and then thin out the aliens so you don't have flash mobs of them just sitting around. While a fence does partly solve this problem, it doesn't completely address it, especially when it comes to move units to/from your outposts.