Unfortunately I suspect you're right @BIWI
It seems that MN users are seen as either "pearl-clutching prudes" or "cool girls/wives" when it comes to sex discussion. This, of course, is not the case. People, mostly women, come here to discuss all kinds of things, and sex is sometimes one of them, and it's great when you see support being offered to women by women.
When it comes to post-childbirth sex I think most of us like to hear "it's ok and normal if you don't want it right now (or ever again)" "it's fine and normal for your body to look and feel different" without the creepy Shrek's Ear vibrator advertising nudging us towards sex. That and with the "vulva-owner" language is completely the wrong tone for Mumsnet and it's hard to believe that the powers that be don't get that. If they don't, they are heading rapidly towards the Trust Thermocline as someone upthread said (look it up, it's interesting).
If the sex topic changes were made because of the Ann Summers collaboration then I'm fairly disgusted by Mumsnet. Yes, they had a thing with LoveHoney, but it wasn't intrusive like this. In fact having a part on the MN website recommending decent vibrators and discounts is fine IMO. These new developments are an intrusion though. Without wishing to sound melodramatic, it feels like a coercion or manipulation. Of course, marketers are constantly trying to get one over on us, but it's just not in the spirit of Mumsnet, as they like to say. That spirit is created with the users and is what makes this place unique, and you undermine our trust at your peril Mumsnet.
The changes to the sex topic are the milkshake that are bring all the lonely middle aged men boys to the yard. It's inevitable and depressing. This has always been a place where feminism has thrived, and where so many women have been taught about independence and boundaries by other women. LTB has become a cliché now, but there are many women who hear it here when they need to.
I have no idea whether I'm just shouting into the void but please @LilyMumsnet (and the rest) just listen to us!