Assalamu alaikum dear sister Queenislam,
You have made a very good point. This is also my understanding on this issue. But before I comment any further I have to tell you all a very interesting anekdote from my life.
It was the first half of 1990's. I was studying in one of the bigger universities in Germany. There was a big number of muslim students studying in that university. Although we had a mosque near the university campus in a market, at just about 10 minutes of walk, the muslim students asked the university to reserve a prayer room for the muslim students. Not only could we get a relatively bigger room without any difficulty, the person dealing with us was kind enough and knowledgeable enough to suggest us, that we could also build the taps for washing in one of the corner of that room. And so we did. We spread a carpet on the floor and made it a nice and cosy place for prayer. We would take a few minutes between two lectures, just come to that prayer room, offer salah and go to the next lecture. Technically speaking it was not a masjid but a prayer room (called musalla) but since we also started praying jum'a prayer there, we would usually call it a masjid.
On one fine day, I wanted to offer salah before going to the next lecture. I opened the door...and what do I see...a big circle of sisters, listening carefully to another sister. What an Imaan-nurturing scene, so I thought. Before I could think of anything else, one of the sisters waked me up from my thoughts and called loudly, "Have you not seen, that notice on the door outside?" Since I was standing just at the door, I just needed to flap the door and there I saw that notice she was talking about. The notice was saying something like, "The prayer room will remain reserved for the sisters from time "this" to "that". Okay, I thought. I closed the door and went to my lext lecture.
Since that happened to many of the brothers many times, we realized we needed to talk to the sisters. We found out, their leader is a german muslima, who was converted in her youth while studying oriental studies. We argued, that this was a prayer room and it should remain accessible to all muslims all the time. But they argued, that they would need a mahram, if any of the brothers was present in that room. We argued back, that the prayer room was not a private but a public place.... So it went on and on. In the mean time, we started respecting their need to have a gathering. After some time, they also realized, that they were creating a hurdle for others to come to the mosque. So they found another place for their gatherings and the matter was resolved with time.
The story might be long and boring but there are important lessons to learn. I will get back to the original topic in my next post.
Wassalamu alaikum.