If a group has been marginalized, belittled, and excluded for long enough, it can damage the people in that group. They can need a safe place to heal, to realize that they matter, that they are as worthwhile as anyone else, and that they don't have to be what their oppressors said they were. A safe place can be very important in that process.
Or a safe place can be a place where a bunch that feels oppressed because somebody looked at them funny, and feels more oppressed because nobody else thinks they're oppressed, can get together and rehash their sense of victimhood and exclude anyone who disagrees.
Human nature being what it is, the second is perhaps more likely than the first. But that does not make the first invalid (when genuinely needed).
Why is that?
Why is someone's identity more important than the content of their speech in this particular case?
Is it impossible for anyone/a man to be against sexism and yet disagree with someone's characterization of an event?
Are all ideas sacred and above criticism now, or only some ideas?
Which ones?
Who gets to decide that?
Why them?
Why does the right of people to be free from criticism take priority over the right of people to have a discussion?
Why does mere disagreement necessarily need to be classed as a negative thing (as you just did?)
How can such an environment foster any kind of healthy discussion, as opposed to me-too echo-chambering?