The joke was that the cult would be against poly because the math would get too complicated and therefore possibly require a degree of some sort.
The weird thing is I think they've lightened their stance against members going to college. It's one of many things they've changed their minds about while continueing to refer to themself as 'The Truth.' I'm pretty sure truth is a constant, something is either true or it isn't. And when you have an all loving, all powerful, omnipresent being on your side how hard could it be to get that stuff straightened out?