Is it Transphobic to know what someone's sex is?

[AssignedPuuurfectAtBirth]

I think we need to definitely and unequivocally know the answer to this

Or alternatively, why not be out and proud and have a trans categorisation?

I think that's easy for us non-trans to say, I can understand why trans people would like to be able to go for a run at the weekend without having to signal their trans status every time. And I would guess in the average park run, there would only be one or two trans runners, if any.

Maybe there needs to be an "Open" category for runners who, for whatever reason, don't want to compete under M and F? This would include trans runners, but also anyone else who wanted it

For me, the word transphobia is used too easily.

An Open Category would work. (But if it is all about participation and not competition, the solution is for a transwoman to register as a woman, fail to use their barcode when they run (which is allowed) and simply enjoy participating).

It depends on the context. Is it transphobic to ask a potential romantic partner their sex? If asking these sorts of questions becomes taboo I can see lot's of potential problems.

Asking someone - are you a woman does not answer the core question re sex. Many people have conflated gender with sex to such an extent that they think they're the same thing. Then if you ask for clarity it's being 'obsessed with genitals.'