I was thinking the same thing. I could see pulling the purse strings, but not talking to the child just seems incredibly wrong to me.
This is the adult daughter's view of the situation. Why might it not just as fairly be said she quit talking to them?
As for the parents' refusing to pay for her education when she has made it clear to them she intends to use that education to become a liberal activist to undercut her parents' values and beliefs, I would say the parents are making a rational and fully justifiable decision.
"but not talking to the child just seems incredibly wrong to me."
I may be that the parents refuse to discuss some issues with her. Her actions are very overtly hostile, regardless of what she says her motives are.
I can see the deep feeling of betrayal Dr. Keyes might experience to cut off communication. After all, do you have any doubt the daughter was practising deception by omission? I'm sure in the Keyes household opinions are not valued just because you happen to like them, but because you can argue their merits. If daughter is holding opinions reprehensible to her father's, and refuses to engage father to give him the opportunity to refute those opinions, what is left?
He either cuts her off, or tacitly agrees to accept her proclivities.