Why did David kill the Prometheans?

>I do have to admit Ridley got me thinking about things long after I watched them just like the first time I saw the space jockey
How's that? There's nothing to think about with Prometheus, it spoiled the horror mystery of the universe by making it an episode of Ancient Aliens.

The Prometheans nearly wiped themselves out as seen in Prometheus. This is 2000 years later and David wiped out the remaining stragglers that huddled around their last working space port hoping they'd find other Prometheans. David came instead.

>there is nothing that implies that is their entire civilization
>hurr durr thats literally all of them!
>despite the fact that they dont even have the black eyes of the original engineers we see in the first movie

That is obviously a shitty colony of an engineer subrace welcoming the actual masters finally coming back showing they havent been forgotten

didn't he mean that in the context of end of the "reign" of engineers, not his own actions
isn't he just aware of the cycles of creation