One example I can think of is how cis people (usually cis males) who choose to crossdress are often misgendered, made fun of, and told they must not be cis because of how they dress.
Though I'm not really sure if this actually counts because these issues I described also affect trans people who are gender Non-Conforming, in very similar ways.
What's more likely is that their comment is just a funny joke, where they swapped the roles of cis and trans in the passage and the joke part is that it sounds absurd and isn't supposed to make sense.