Why can't you simply say "women"? What's the impediment? Why do you so cling to "girl"?
Now if we agree on that, then to make any absolute claim that calling a woman a "girl" is demeaning then we must either make some universal claim about the intent of all those who use the word or a universal claim about the reaction of all those that hear it. I think either of those claims might be overreaching. Or maybe I'm just setting the bar too high.
We obviously live in different parts of the world with different social expectations for language use. Beyond a certain point, arguing about when it is ok to say woman or girl is just pointless bickering over divergent cultural expectations and nothing more.
I respect your viewpoint, you have definitely made me think. I now consider myself a Level 3 misogynist (up from 1).
I never really considered that calling a woman a 'girl' was a way to demean or lower them in status (I do use the word on occasion). I think the key difference is that I would never address a woman as a girl ("Come here, girl") but I may refer to someone as a girl if she in her 20's or younger ("Hey, that girl dropped her college id, can you give it to her?) Or I might say "Do you want to see if any of the girls in accounting want to go to lunch?"
Is this really the bar for modern-day sexism?