That last one is a great blanket excuse for lots of things, it's the AI War equivalent of "they're on the ship with Boxy."
True -- but I also find it interesting, thematically. And really, the game wouldn't make any sense without it. I had recently been playing Red Faction: Guerrilla right before making AI War, and it was on my mind. And the only reason that you can be a cool insurgent and do all this stuff there is because, most of the time, you just blend in as a citizen. But, of course, when you piss off the AI then they really start to notice you and send swat teams, etc.
Given that I wanted a similar guerrilla warfare feel here, too, I needed a reason for the AI not to look at you a lot of the time. I wouldn't even call it an "excuse" per se, as it's not like it's covering a technical shortcoming -- the AI is quite capable of happily killing you, and if I'd wanted a smaller-scale direct-conflict game it would have been possible (that basically describes the game every time you attack a new planet, or every time they send a wave at you, really).
But anyway, I do think it's a prerequisite that if you're to engage in guerrilla warfare against a stronger opponent, which is the point here, that you opponent not be aware of you. Otherwise, in any situation in real life or in any game... they'd just crush you. In any FPS game, if all the enemies in the level just ran at you and knew where you were all at once, you would die every time. I just found it odd that had never been done previously in an RTS context.