Yes, it is accurate to say that "statistically a new female hire in an IT shop is likely to be a designer, not a coder". It is factually accurate to say that, but is it right and moral and nice to say it?
Words can affect people, and set tone and expectations. Is it right for all us men to presume, unless shown otherwise, that the new female hire is not a coder? Will this help or hurt our industry? Every little teeny thing (like presuming this (which is a teeny thing)) can be detrimental and can build up. "Death by a thousand cuts", "Straw that broke the camel's back", our society recognises that sometimes lots of little things can be Too Much™ sometimes.
Would software/the company/society be a better place if we didn't vocalise these presumptions about women, especially if it reinforces negative stereotypes about them?
After all, we all know the mistakes that can come when a female starts getting bigger and we ask "Are you pregnant?". Manners say to be careful here, let's apply some manners, rather than fetishising statically accurate deductions, to presuming women aren't coders.