It's not about being offended by penises, it's about wanting to have agency over whether, when or how we want to see them, to know who were are agreeing to allowing to touch us intimately, and to know that we are safe when we are in a state of undress, ill, or otherwise vulnerable.
As most men are bigger and stronger than most women, and as transwomen were socialised as male, and as most men are sexually attracted to women, and as most violence is committed by men, and as the vast majority of sexual crimes are committed by men, and as many women belong to religions that forbid sexual touching or being alone with members of the opposite sex outside of marriage, women have organised and demanded spaces where men may not go.
Not only that, but women organised and fundraised and campaigned to provide refuges for women who were fleeing domestic violence.
Now men (supported by some women) want to take what women have built for ourselves, by deciding that they are women too. If we complain, we are told it is because we are bigoted, prudish, 'offended', or that we have 'a victim mentality'.
Not only do we no longer have the right to single-sex spaces, but we no longer have the right to call ourselves women, or mothers unless men have the right to do so too.
They bleat 'but what about transmen?', not because they give a tuppeny one about the women who have 'transitioned' (many of whom have deeply regretted it), but because most transmen are smaller and lighter than most men, were socialised as women, and are unlikely to pose a sexual threat of any kind, so feigning concern for them gives an air of equal opportunity, when in fact the women, in both cases, are the ones to lose out.