That's weird, I've kind of been assuming this whole time that War for Cybertron was a prequel, leading up to launching the Ark. I mean yes it's got Ultra Magnus and co. but it's easy to assume they were around but missed the boat to Earth, and were busy somewhere else when everyone woke up in the 80s. Was Unicron around back then? Like maybe they used to send him a pizza every now and then to keep him happy, but that was Starscream's job and he forgot to delegate to anyone before he left, so the poor dude's just been waiting out on the edge of the galaxy getting progressively hungrier and more annoyed for four million years until he's finally lost his temper.