I'm not entirely sure i agree, woollyminded. I don't know that it is effective calling them out. They are perfectly aware that what they say is often heinous. The only point of what they do is to derail and pollute. Engaging is, I suspect, futile: it gives an opportunity to respond, promotes the illusion of engagement (when there is none), and derails.
The only thing they want is to basically destroy a communicative space. They don't care about what is said. They have no interest whatsoever in the value of communicative exchange - other than to seek to destroy that value.
I honestly think a cordon sanitaire around them is the best approach, along with an ability to tell others to do it too. At the moment, you can't even warn people that this is a real internet thing, and that Poster X is behaving in ways synonymous with these social media pollutants. Which is beyond absurd.
It's particularly upsetting because they attack one of the really valuable aspects of Mumsnet: its ability to host interesting political communication - predominantly (though not exclusively) amongst women. And that, of course, is why they attack/target it.
I see your point about educating people about codewords but ... it is very difficult to call them out without effectively falling victim to their strategy.
It's difficult: since the aim is to pollute - to make a social media space unusable - it is quite tricky to deal with them: engage, and they dominate conversations; ignore, and they get to dump vile language/posts on threads.
They need to be dealt with, though, because the aim is to destroy particular communicative areas of Mumsnet, make them utterly unusable (specifically politics and feminism) - and with the MRAs, they just don't like women talking together, full stop (I suspect). That is a problem for all of us (MNHQ included).
It would be grim if the actions of some men (and I think a lot of them are men) turned MN into a site where we can only talk about things like make-up and food preparation (great though these things are) because a group of angry men (and libertarian trolls) managed to exert their way.
Fuck them. 