Well, the one snag in your plan is that the AI isn't actually needed for anything. Running a fission reactor doesn't need an AI, and doesn't even need a computer. An analog circuit, even a mechanical mechanism, can do it. Waking people up would just take a clock. Dodging debris just takes a vintage radar system and steering control running like the inverse of a missile seeker head (the original Sidewinder used only seven vacuum tubes to track, intercept, and kill). If you can freeze human embryos, then you can freeze anything else, so you don't need to maintain any type of ecosystem. It's a cargo barge with a star tracker, a radar, and an engine, and that doens't take much more sophistication to run than our Voyager probes from the 1970's.
I also forgot to mention threat #1615: Space pirates from Earth who board the ship, kill off all the male embryos, and set their cryochambers to wake them up on the planet when all the female embryos are turning 18 so they can live on a planet of women.