Well, I would say that you should actually read Vonnegut instead of using his quotes in ways in which they weren’t intended.

Because I can assure you, he didn’t make that statement in support of the left shutting down productive communication with each other by accusing each other of being “closeted” liberals.

The close mindedness is going to make you fall victim to things worse than liberalism if you decide to not work on that current but fixable flaw.