No one is ever themselves, unmodified, when around other people. There are jokes and attitudes that are unacceptable in stereotypical masculine social situations too (having a feminine interest, for example, or simply speaking in the wrong way).
The Overton Window moves. It narrows and widens. That isn't the same as being unable to be yourself.
I agree that men should be socially allowed to have spaces where women are excluded and society does sort of tend to look down on that kind of thing, but I also think that in a world where many professional environments are still male dominated some sensitivity to the exclusion of women is warranted.
I mean plenty of jobs out there are still 95% or more occupied by men only.
Sweden has a government department for statistics and one data point they collect and publish is work statistics. The most gender segregated work places are dominated by women, with a few being around 99%. The only male dominated profession in top 5, last time I checked, was stonelayer, which was around 95%.
In term of total gender segreation in the work force, about 15% of men and women work in gender equal profession. The majority, both men and women, work in a job where their gender outnumber the other gender by 2 to 1 or more.
A common finding in studies conduced on this statistics is that gender segregation occurs also within a profession. Teachers is used as the typical example where gender segregation occur on both subject but also on level. It also get worse as people advance in their careers, with each "step" on the ladder being a point where the minority gender decrease.
> No one is ever themselves, unmodified, when around other people
I see what you mean. To clarify: I meant as a group, rather than as individuals. I appreciate there are smaller-groups that also can't be themselves somehow, but if that's a sin, then perhaps the larger group not being able to be itself is a larger sin.