I think the themes here are great. It will be interesting to see how the author writes it moving forward.
Why exterminate when you can have a nice and obedient race of slaves?
Look at it from the perspective of the Aliens. Without knowing their culture or history I'd assume their sense of ethics and morality is going to be completely alien to ours. Being a spacefaring race there's going to be a superiority complex, you'd expect Humanity to suck you off since that's all they can do. You saved a planet of primitives from extinction and they even worship you for it, of course you'll act smug about it. It's a nice planet too, just shower them with scraps of your technology and they'll lap it up.
A few more generations and you'd have their culture so dependent on yours that they're basically a slave race worshiping the ground you walk on. It's already happening since you can get away with paying them peanuts in wages. Then there's that little theory of Kitami's: why wait for something convenient when you could fake a catastrophe and capitalize on it in short order? Send a rock on a crash course, wait for them to panic, then "save" them. With the difference in tech they can't prove you sent it hurtling along in the first place, and they wont if you have anything to say about it.
Yet this story is from a Human perspective. It's from the perspective of people who've been snubbed by these supposed "saviors" and they're treated as second class citizens. You've had nothing but bad experiences with the Aliens and it doesn't look like you're benefiting from their technology either. Naturally you'd resent them, and since they're not Humans this little thing called morality won't get in the way of taking your frustrations out on them.
The eating them part is gross, but think of it this way: you're living paycheck to paycheck on unhealthy instant food with destitute poverty being the only future you can see for yourself, just when you're finding yourself a little desperate a pile of fresh meat just fell in front of you. Laws be damned you have nothing to lose and tomorrow you won't be starving. Kill em' and grill em'.
