I'm glad he's ok! That's how I got Luna, someone threw her out of a pick up truck, they were 2 cars ahead of our car. I watched them throw out a bunch of junk, and I saw the carrier (not even a real 1, like child's toy) go by with Luna in it. Luckily that carrier took most of the hit, that's the only reason Luna was ok.
Ugh that makes me sick that someone did that to that sweet kitty but glad he's doing ok. I rescued a kitten a few years ago that was thrown from a vehicle and he had a broken leg. Thankfully the Animal Defense League took him in (no kill shelter.) I hope he got a great home.