We all know that Rick and Morty is dark, and often it is at least somewhat acknowledged by the show/characters (usually Morty). And definitely by us fans. In Promortyus though, everyone seems to overlook the darkest aspect...not the 9/11 joke but the fact that they massacred countless SHIPWRECK SURVIVORS. While murdering the absolute shit out of them they talk about how it is nice to have guilt free fun and killing, but they aren't just killing the parasites but also the poor hosts. Rick and Morty show that you can be freed from the face-huggers by having them removed and survive and regain your personality. Admittedly it might have been a pain in the ass to remove all of them, but Rick IS a genius and could have found a way. Of course they are faceless aliens that we might not care about as much as Rick and Morty but it is kind of like having a bunch of people with tapeworms and you decide to shoot them all rather than give them meds. And of course at the end they apparently make sure to kill virtually all the hosts by making them give birth, and then leave a million eggs waiting to start the cycle again

Edit: Final side-note, how does the Glorzo survive/grown in population. Apparently each egg only births ONE Glorzo which makes the host birth a new egg (with ONE Glorzo) and then dies. Meaning they can only replace themselves, not actually add to population. Also any Glorzo that dies and isn't able to reproduce can't be replaced, so wouldn't population just steadily decline? It is an illogical reproductive cycle