GailCindy since you asked, and there may be lurkers who are similarly confused (and to be fair, TRA discourse does deliberately confuse people into thinking 'cis' is just like 'straight' or 'NT'), I'm going to reply with the assumption that you're posting in good faith.
The problem with 'cis', and 'terf', and the title of the talk guidelines in this section, is that they all presume to define us women and our feminism not in our own right, in relation to our experience of what it is to be female, but only in relation to transgender ideology and 'trans rights'. As if women have no stake of their own in what 'woman' means, no right and no reason to discuss an understanding of womanhood or of feminism, that doesn't centre transwomen and then redefine us in relation to the new centre (meet the new boss; same as the old boss, of course).
Further, 'cis' is innacurate, problematic, and offensive because it asserts that those of us who don't identify as trans / NB can therefore be presumed to be comfortable with / to identify with the 'gender role' we were 'assigned at birth'. Feminists reject the notion that adherence to sexist stereotypes is what makes a person a proper woman or a real man, and that being male or female should determine a person's social roles... that's what makes us feminist!!
Can you not see how an ideology that asserts that personality determines 'gender', which then supercedes sex in determinng what it is to be female or male, is every bit as regressive as the presumption that generarions of feminists have struggled against, that sex determines personality, aptitude, social role? Both positions accept that 'woman' = a person who fulfills a stereotypically feminine social role... How can you expect feminists to accept that definition? A 'cis' woman in the 1800s would be one who doesn't think she should have a right to vote, wear trousers, or work outside the home: happy and satisfied with the 'gender role' assigned to her due to her sex. Does that seem feminist or progressive to you? And a born female who felt uncomfortable and contrained by that role would be, what... a transman? Not a proper woman? Someone who could or should just identify out of all that oppression and leave the 'cis' women to their second class citizenship?
Luckily for us, our foremothers understood their womanhood to be defined by their having been born into the female reproductive sex class, and were therefore able to act in solidarity with each other and with us - future members of the same reproductive sex class - to question, challenge, fight against and largely dismantle all the other bullshit that constituted social and legal understandings of 'what it means to be a woman.' That's why we can work, and fight for equal pay, and vote, and be elected to office, and enjoy a thousand other freedoms that we take for granted that they did not have. And we owe it to our daughters and future generations of our sex class to continue the struggle - not to go backward into believing the stereotypes are true and the biology isn't. Not to embrace an individualist, misogynist ideology that disregards reproductive biology as an axis of oppression and undermines female solidarity.
It is an insult to our feminist forbears and to ourselves and our daughters to accept this new orthodoxy that women in general and feminists in particular no longer have a right to discuss 'what it means to be a woman', without defining us according to the ideology we reject, and renaming our centuries-old feminist discussion about womanhood as being about 'trans rights' instead.