If you want a closed door meeting with this professor, ASK THEM. A closed door is to stop eavesdropping, but that doesn't necessarily stop eavesdropping. . i used to eaves drop on geology department faculty meetings because there was one ich gap underneath the door. and glass panel in the door as well.. Some doors ARE pretty sound proof. I think the office door was open when he denied me permission to take one of his seminar glasses.. of course i was upset, but he did have that right. i got over it.
Grow up, little girl, you are not being discriminated against.
As someone else has already pointed out it, it is safer for YOU when the office door is open..Girls CAN be sexual predators to, so it is safer for BOTH of you in some ways when the office door is open. Yes i HAVE been asked if particular professor was sexually discriminatory toward me.. My answer was no. he's still been pretty well ostracized and isolated and he is not allowed to teach anymore, so he has plenty of time to work on his blog.. He has tenure. He cannot be fired.