It's a sub-thread for people with shared experiences. There are a couple hundred such sub threads on Mumsnet across a wife range of subjects.
For example here are all the subthreads in the main Health thread:
Addiction support
Alcohol support
Allergies and intolerances
Autoimmune disease
Child mental health
Children's health
Coronavirus
Dementia & Alzheimer's
Diabetes
Eating disorders
Exercise
Family planning
General health
HCP Chat
Life-limiting illness
Menopause
Mental health
Stop Smoking
The weights room
Women's health
Technically you could just put Menopause into a general Women's health section. Or even just a Health section. Why does it need its own subthread?
Because for those women going through this life-changing shared experience it's easier and more user-friendly to have all their threads in one place. If you are not going through the menopause right now you probably don't have anything useful to contribute - unless you are a doctor, or other medical professional specializing in this area, or perhaps a concerned family member asking for advice for someone else.
You may want to hang out to read in this thread if you are a younger woman (to see what's coming) or a man (to see how to support a partner)
No one has banned you. But you probably won't spend a lot of time in there if it's not relevant to you.
If you are one of the people arguing why this new forum for black Mumsnetters should exist, are you struggling to understand that there's a need for this particular shared experience?
I'd recommend that instead of complaining about it now, you spend a couple of weeks checking out the new thread, reading the different topics which come up and learning a little about the cares, concerns and issues of our black communities. Their shared experiences.
You are not banned - there may even be places where you can contribute.
And if it doesn't interest you in the slightest then just don't go to that thread - I'm sure there are loads of subthreads you never venture into - how many times have you thought deeply about the SN wheelchairs and mobility aids thread?
Having this exist doesn't take anything away from anyone else.