In a world dominated by, among other things, cis heteronormative patriarchy, it would just be nice, for once, to have a conversation not taken over and derailed by a member of a dominant group wanting to make it all about them (or to have to list a bunch of caveats and stipulations in advance to try and avoid these situations, just for them to be ignored anyway).

As a rule I don't gender people unless they've made their gender clearly known, or, very rarely, if they've given me glaring contextual clues. You're absolutely right of course that having testicles doesn't mean someone is a man, but barging in to a conversation by and for marginalised people about taking up space in the world that marginalises us, to make it about their act of marginalisation, is a classic cis man move. They don't even have to mean to dominate every space they come across and try to centre themsleves in it, which just goes to show how ingrained the entitlement is.

Do I think I was wrong about that person? No, I really don't.

Do I regret how my reply has impacted you and potentially others? Yes, that wasn't my intention and I apologise.