Samantha, I would encourage you to refer to this as “cisgender centered”. Not cis-sexism. Here’s why.
As you probably know, both cis- and trans- are Latin prefixes. Cis- means to stay in place. Trans-means to move or change place. To say, cis-sexism literally means to not change one’s position on sexism. Transexism would literally mean to change one’s position on sexism. It is sexism being modified. Kinda doesn’t make sense in this context. In fact, what it is meant to communicate is cisgender-people’s-sexism or the sexism of cisgender people. It is a possessive of sexism that has lost its grammar with the contraction.
Sex, as you know, is biological. This gives rise to highly confused individuals like this who can use this unfortunate terminology to make a point. https://www.reddit.com/r/GenderCriticalGuys/comments/9pcfp6/when_transsexual_becomes_transsexism/
The term cissexism was coined because the idea is analogous to sexism and Serano is making the case that her idea stems from the classical notion of sexism. “Cisgender centered” would be more linguistically correct to say for your examples, like “ladies and gentlemen”.
Even Serano’s own definition makes no reference to sex, though it is the root of the word. Odd choice then, isn’t it? Serano makes an interesting point about how transphobia is rooted in sexism, but the artistic license needed to come up with cissexism is unproductive.
We don’t say male-ism and female-ism, we just say sexism. Similarly, we should say genderism, not cisgenderism and transgenderism. Genderism should be understood to mean the belief that gender orientation confers dominance. That this dominance is with the cisgender category is obvious, just as it is with males in sexism. In your piece, I think “cisgender centered” would do be more clear.
To include Serano’s viewpoint, just say that this cisgender centered view is rooted in sexism. We can all do without the new and confusing term.
Why does it matter?
Cissexism is really an attempt to stereotype cisgender people as sexist, the same as saying “white people’s racism”. Just as not all white people are racist (in the classical sense of that term), all cisgender people aren’t sexist.
It is already the case that many people consider the harmless prefix cis- to be a slur. Why provide evidence? The next logical step would be for someone to coin the term cisism, making cisgender into an ideology. Do we really think this is going to help transgender rights issues? I don’t know about you, but my transgender friends do not support these aggressive tactics. I say aggressive because Serano knows what she is doing.
Even worse, this misapplication of the Latin prefix cis- for everyone cisgendered is regarded by many to be a slur and here they would have reason to believe that is the intent.
Better to use the prefix as originally intended to avoid unproductive conflict. I’m sure Serano is quite capable of being more eloquent if her intentions were otherwise.