Two reasons. At least.
Firstly there are currently PhD students studying Mumsnet and their bad opinions and reactions, and scraping the data illegally so need to renerate some bad opinions in order to study the responses. See the Aston University debacle, all the universities that are studying language, language models, and any internet or AI in general will be doing it.
Secondly, they are using massive data bases, including Mumsnet, to inform future AI. This is at a much higher level. This is the largest database of female responses probably in the world so it is a massive target for 'teaching'. Unfortunately the AI itself is tainted so all responses will be filtered through lenses that don't exist in women's viewpoints.