Nice hypothetical, can you come up with a real example of such a brave and controversial statement? Because I'm not sure this actually exists, most of the tube "x-ism" is also "being an asshole for no reason".
I would direct you to Vaclav Havel's book "Power of the Powerless" - where dictatorship of the ritual is spelled out and how he amazingly identifies the traits of post-totalitarian societies. I believe heresy is one such trait.
I would also add that my main issue is with this flippant attitude towards the greater issue: that heresy is alive and well and trumps everything from science, truth, evidence and context.
Answer me: who defines x-ism/x-phobia? Remember if such a tool (heresy) exists and it is effective then your enemies get to use it too.
You're the one saying that there are some sacred truths which cannot be uttered on pain of ostracism. Citation required, because I can't prove or demonstrate a negative. I would direct you to "Basic Logic", an introductory textbook by Raymond J. McCall.