First, here's the embed for ease of listening if you're interested in the show:
Lots of reference was made during this episode to Dr. E. Michael Jones' book Monsters from the Id, but I neglected to provide a link. Don't buy it from Amazon where they're asking for something like $70 for a used copy. You can get a new paperback version for $24.95 from Fidelity Press: http://www.culturewars.com/books.htm
The main thesis of his work is that, the moral order, when suppressed,
reasserts itself in the form of an avenging monster. The eponymous alien from the film is the epitome of this -- the unstoppable, remorseless reassertion of order. One of the guests mused that the characters in the film hadn't done anything wrong to merit this wrath, but it occurs to me that they simply represent modern humanity. This would be subconscious on the part of the movie-makers, their very purposeful imagery otherwise, notwithstanding.
I tried to do a more obvious and straight-forward take on this in All the Gods of the Gentiles, where characters' sins lead directly to the unleashing of the monsters.