Just wanted to say a tested this as the Iridium Corporation today, and it doesn't work for them either.

My guess is that even if you were to reduce it to 2.5 pop, Prolific species would still bug out as that would still equal 5, plus min colony ship pop of 0.5, for a total of 5.5.[2.5 + 2.5 + 0.5 = 5.5 pop colony ship]

So 2.2 billion is the highest the ideology trait could grant and still potentially work for all factions(if that's even why it's broken).[2.2 + 2.2 + 0.5 = 4.9]

At that point the ideology trait seems quite weak, and may need to be buffed in other ways. Perhaps give new colonies an extra growth % modifier to help make up the difference.

Edit: Billion, not million.

    One possibility would be to duplicate the Prolific trait, but this would give prolific species with this ideology triple population.  Another is to duplicate the Colonizer trait, a free building.

    However, I think a free building can be abused (free hyperion shrinker!).  I'd rather add +30 or +45 stored production to a new colony for the colonizer trait, and another +30 to +45 for this trait.  Most level 1 buildings are 30 production.  Being able to soil enrich + build on the first 2 turns would be nice, now that we can store production.  Would also remove the rush build bug with the colonizer trait (deleting the first building you place removed the rush).

Despite what the tooltips say, the Hyperion buildings affect all ships built on all planets, not just the planet they are built on.  As to whether they all actually give the bonus they claim I can't verify.  The one that increases ship capacity seems to.