Gretchew would hardly make the difference if we were ever in a position to be able to annex Terran. That's not the motivation. Terran will always have the obligatory defense of the Astrocracies anyways, right? Charter and all that? Phantaria will never be in a position to war Terran ever again.
Besides, a theocratic city-state would be awesome.
Who said either of you get Gretchew?