aliens are already dead. Obviously, aliens should be about the classic sci-fi movie and not about aliens. Why are we even talking about aliens? Surely a conversation specifically about aliens would be off topic here? Oh... that tag has already been removed.
Can we also get rid of the zombies and vampires tags as well? I suspect that the bulk of these are going to be used where the genre tag horror is applicable, and the rest of the time they're going to be used on identification questions, rather than just being stated in the body of the question.
Indeed we should remove those tags, those are general topic tags which don't have any use here, as already explained to some degree in your linked question. Afterall we're not going to introduce tags for each and every possible thing depicted in a movie, cars is already being misused frequently for that.
For the purpose of discussion (in the same way as the sex discussion) to vote for this answer would be to say that we should keep these tags for the purpose of questions that relate to zombie or vampire portrayal in movies or TV in general, or to tag ID questions that include them.