I think most genetic women find their periods to be an inconvenience, a nuisance and, for many, debilitating (cramps, headaches and worse). Yes, they are also part of reproduction and motherhood but by and large I'm sure most women would switch them off if they could. It seems to me though, that as trans women, we see it as something that women bond over, because it is a shared experience and something that men are not included in discussing. "Secret women's business"... as they might call it in Australia. Talking about menstruation gives women an option to show empathy and support and sisterhood, so it's no wonder trans women feel it is a potential grey zone for them.
Anyway, I went and bought a small box of tampons to carry in my purse. I might not need them but I can show a bit of support should someone else is caught short.