Just as a tangent, the term for this is 'hypergamy' and one can find more research and writing on it searching for that.
I think they probably just thought that the term hypergamy sounds cool, so they adopted it to appear scientific.
I 100% agree with this, however the way they use the term does fit in perfectly with its definition.
More relevant answer in this case: it's a term frequently used as a cudgel to shut down conversation. It's a fallacy of association, and thus can be safely ignored.
"I like dogs."
"Oh yeah? So did Hitler!"
That sort of thing.
"Redpill" has come to mean many things on the internet, but all trace their origin to the movie The Matrix, in which the character Morpheus offers the character Neo two pills: one red, one blue. If neo takes the red pill, he will be pulled out of the Matrix (a computer simulation) and showed the real world. If he takes the blue pill, he will continue to exist in the computer simulation and can pretend it's the real world.
In the case I was referring to (redpillers using "hypergamy"), "redpill" or "to be redpilled" means to believe that male/female dynamics are entirely sex-driven regardless of context (professional, sports, relationship, etc) and furthermore those dynamics are governed by rules established early in human evolution - for example, they believe women will only want to be in a sexual relationship with strong men that can provide for them, or that women universally prefer to work as little as possible while being provided for by men.
A redpiller himself would probably take a mildly different definition than this - they would try to sell the community on its less politically incorrect values, such as the tenant that men should focus on self-improvement, bodily health, careers, etc. However, this is typical cult behavior, and the darker parts of redpill are what truly drive the community.