Apologies for mega post, am passenger on long car journey and currently not speaking to DP 
Random , your post made me feel quite emotional. I used to pride myself on being a good trans ally, particularly in support of my trans man nephew, and his circle of friends. My nephew was mercilessly bullied at school for being a gender non conforming lesbian, and has solved the problem by gradually coming to identify as a man. Much happier, and has a surprisingly large peer group of trans identified females in our small town. I have oscillated between feeling so happy that they and their group of friends are able to support each other, and feel happier in their own skins, and also worrying about the long term effects of the blockers and breast binding which proliferate in their circle, as well as, as they are 'coming of age', the transition on to cross sex hormones, which I feel they have sort of been egging each other on about for the last couple of years.
It is with so much reluctance that I have engaged my brain in the uncomfortable task of learning about the 'terfy' side of this coin. Initially, it actually came through reading stuff my nephew was sharing on social media, pertaining to the irrelevance of biology, and having to do more double takes than my brain could keep up with.
Then, being a teacher, who had previously been relaxed and unbothered about the possibility of gender non conformity and trans identified pupils in schools, I began to come across training materials and policies which effectively outlawed reference to biological fact as having any relevance. Someone said right at the start of the thread "They (users on Fem Chat) call people penis-owners." . In my experience, this odd phenomenon has originated not on MN FemChat or in rad fem circles, but with the insistence among those who support trans ideology that biological fact is irrelevant, exclusionary and offensive to trans people. Hence the use of terms such as 'chest feeding', 'prostate owners', 'menstruators' and 'pregnant people'. Whereas I will always use preferred pronouns out of politeness, and not dead name anyone, I draw the line at disregarding chromosomal, binary biology, ie 'trans women are women'.
Someone also poked fun at women worrying about 'being anonymous on Twitter'. There was a WPUK meeting (a meeting to discuss the impact of the GRA (Gender Recognition Act) in my city last week, which was not picketed by trans rights activists, as they had not, despite ardent efforts, been able to find out the location of the meeting. A very vocal, local trans activist group are now relentlessly circulating a photo from the meeting room (showing the panel speakers sitting at a table) , menacingly asking people to come forward if they know where the meeting room is located, so they can hold the owners to account. Once you are familiar with what 'being held to account' by trans rights activists entails (threats, violence and doxxing, which is the awful practice of contacting someone's employer and insisting on their dismissal), you really want to ensure anonymity.
Radio , I get you and I think yours is a fairly common perception.
Skip , mind-bogglingly, in the example you raised, the trans woman having sex using their penis, is using their female penis, as identifying as a woman. This is trans ideology at its trickiest.