I don't think it would cause conflict or be anymore exclusive than it currently is. There was conflict when the sub was first created (some men were not happy and let that be known) and Bob basically told them to get over it because it was non-negotiable. Having the forum be restricted would definitely cause conflict, just like everything new here causes conflict, and it could be handled the same way the prior conflict was handled.
I would love to be able to ask more intimate questions here but I don't feel comfortable having the more intimate aspects of my life available for all to see. I ask those more intimate questions in my women's-only FB group so it works out well.
Just examples of wtfreak situations that still blow my mind - 1. a woman in one of my co-ed vandwelling groups asked about how to handle her period on the road and she got blasted with comments from men that that wasn't an acceptable topic and that it was simple so she way dumb to ask. 2. A woman stopped about how other people carried their makeup and she was blasted for being high maintenance and told she wouldn't make it on the road. These same men tied themselves in knots helping guys fit in complete gaming systems, big screen TVs, and even an ATV, but this woman's makeup crossed the "too much" line. Thank goodness for the safety of women's-only groups and forums.