I'm a woman, too and have had to fight for my rights and have fought for the rights of all women.
You could try to say, because I don't have all the same reproductive organs as you, that I'm not a woman, but you would then be left with a bit of a conundrum: reducing me to my reproductive functions (or lack thereof) is exactly what you are objecting to. You can't object reducing women to being menstruators then proceed to define women as people with a certain set of reproductive characteristics.
For the record, I don't know that that is what you were implying. You seem to have agreed that trans women are women.
So I will repeat what I said previously, that the idea is not that women were called "menstruators." The idea is that not all who menstruate are women. How would you refer to a man who menstruates? If you think menstruation makes him a woman then you are defining womanhood as one who menstruates, and would be arguing against what you've said here.
If you define men who menstruate as men, however, and someone is talking about everyone who menstruates--men, women, nonbinary people assigned female at birth--what are you going to call them? "Women and others who menstruate?" Maybe just "people who menstruate," or, yes, "menstruators."
By the way, the article was only talking about people who menstruate so it wasn't even talking about all women. Post-menopausal women, women without wombs or ovaries for one reason or another (from hysterectomy or perhaps born without) don't menstruate but are still women.
In other words, no one is using the word "menstruators" to refer only to women, and--to the extent they are referring to women at all--they are not talking about all women. It is indeed a straw man argument to say that women are being reduced to "menstruators," also a hypocritical one for those who think menstruation is a condition for being considered a woman.