This might be a long post, apologies, have been thinking about this for a while now.
Is it ever acceptable to call a 32 year old a young woman? Yes.
Tell my aunt who upon finding out that her only child, a grown woman, a doctor with children of her own, had been in a terrible accident that left her with life-changing injuries, that she shouldn't weep for "her little girl, her baby".
Tell my friends who crowded together at the graveside of one of our own, a beautiful 30 year old that we had grown up with from the age of 5, that they shouldn't have referred to her as " just a young girl, really, with so much of her life unlived*.
Or indeed, let's not pretend that senior officers in our armed forces don't refer to the troops who serve on our behalf as "the boys". Because they do. Why? Because their families have entrusted their care to those same officers. It's not a job where the worst that can happen in their working day is that they lose an account, or mess up an order, or even just get fired. Their families entrust the care of their children, no matter how old, to their senior officers. Those officers and superiors become, in effect, their parents whilst they are on duty. I don't imagine the families of the police forces feel so very differently.
In that context, yes I think it's acceptable to refer to them as young girls. IIRC the phrase was used by a families liaison officer who had just left the grieving relatives not a few moments before. The relatives who probably were weeping for the loss of their little girls. The officer concerned probably considered them part of the wider police "family" so using the words that their blood relatives may have used probably didn't seem out of place. Conjecture on my part, I know, but not beyond the realms of possibility.
In the same way that it's possible to be outraged at the tragic event and pissed off at the same time with the use of the phrase "young girls", it's also possible to be against demeaning language used to oppress women and to denigrate their professional achievements and understand why the phrase "young girls" was used in this instance.
And hully you may not care what "emotive flannel" is thrown about, but that just makes your words IMO heartless and unfeeling in this instance, because the particular circumstances of the use of this phrase are emotional. And linked to tragic murders. If you can't understand that there is a time and a place to give a shit about these things, then I despair for the wider feminist cause.