Sadly, many of us felt that way once, some still do.
When you (General you)start extrapolating it out to the end point of that thought and how it could practically be applied, you start realising that a post operative line in the sand doesn't work at any practical level.
They are still male. They still have many aspects of their personality and their body that is male and there is simply no way to check operational status.
I have sadly come to the understanding, there is no way to differentiate.
And as we are told, to expect any one to have traumatic surgery to fulfil a requirement that will mean access to female single sex spaces is transphobic. To make the line 'passing' is transphobic. And is a male having lost a penis due to disease or trauma allowed in too?
So, therefore. the line needs to be male. Plan and simple - male. Once a male, always a male.
Male's without a penis, are still male is now my line. And no males in any female single sex spaces after they have reached around 8.