Heavily buffed factories can survive a nuke. Once we get replays it will be easier to track down this sort of thing though.
I was your ally in a game and your thought the other side were cheating. You were mostly against Creature of Existance I believe and I really can't see him cheating at all. What he does do is put more quanta into upgrades than anyone else so his stuff is really tough.
Anyway, as I say, once we get replays people can show what they mean if they suspect cheating. There was a cheater a number of months back in base Ashes, (he was able to get a lot more units than possible), so it is something devs have to be vigilant against of course.