It's difficult to see two lots of people who are both discriminated against in various ways directing their anger at each other.
I can see why some women find it galling that someone born and raised as a man should have as much of a voice as they have in defining "women's experience". Obviously that person has had a totally different experience, and will do as long as society continues to treat men and women as separate & different groups. For one thing, in a sexist society that person has been able to "pass" as a man, and reap the benefits that that involves - something that women-born-women cannot do.
On the other hand the person who feels at odds with the culture of their assigned (male) sex is going to be oppressed by society as well. First by being denigrated by a patriarchy that values "male" behaviours above "female" behaviours, then being alienated from a society that values the gender binary and views their very existence as an affront to the law of nature.
But TBH I think the fact that some people who were born male want to identify as female is the least of our worries. That's as long as transsexuals don't claim to have an equal or superior view of what "womanhood" involves - rich as that concept is in the experience of being identified female from birth and encountering the biological facts of being female. Both women and MTF transsexuals are subject to abuse, discrimination, misogyny, rape, assault, hatred etc etc etc - the whole sorry catalogue.
Ideally there wouldn't be a third sex, ideally the idea of your sex being a totally defining part of who you are - your interests, appearance, abilities, mindset all being dictated by it - would die out. But as long as MTF transsexuals are subject to the same ill-treatment in society because of their female identification - i.e. because they look like women they are being treated as badly as other women are - I don't have a problem with banding together with identifying women no matter what shape they were born.
We've got a common enemy and that is a culture where femaleness is hated and undervalued and attacked at every turn. Regardless of how some of us got here, we're all under the heel of the patriarchy's boot now and might as well work together to rebel against it.