This whole thing is weirder than it appears, so bear with me if this seems a tangent. The new guidelines do not ban anti-capitalist groups from schools, they ban anti-capitalists groups from teaching Relationship and Sex Education (RSE) which is all the guidelines relate to. RSE has obviously been controversial with the protests against No Outsiders, whilst gender critical activists led by the seemingly obsessed Tory semi-grandee Baroness Nicholson have been lobbying hard to kick trans charity Mermaids out of schools (*spoiler, Mermaids barely go into schools anyway and even then only to train teachers not kids - according to their annual report they only delivered 138 training sessions to all kinds of organisations in 2019). This group are utterly convinced that insidious forces like, err Stonewall, have been going into school persuading gender nonconforming kids they are really trans and are equally outraged that LGBT inclusive sex education means actually telling young people how LGB people sometimes have sex. References to anal sex in particular has been one area of major concern with the LGBT charity The Proud Trust attacked over admittedly quite cringy teaching aid that gender critical activists felt gave the message to girls that is was okay to have anal sex. Just as an aside , there's shades of QAnon here with some, but by no means all, activists thinking this all represents some dark paedophile plot to sexualise children and undermine consent.
Last week Liz Truss anounced the Government would not be going ahead with reforms to allow trans people to self ID if they want to change the sex on their birth cerificate, however her announcement fell short of her earlier somewhat unexpected pledge to strengthen the law around single sex spaces and prevent children from making lifelong decisions about their bodies (which some had hoped meant a move to ban trans healthcare for young people). This announcement appears to have thrown the government into disarray with big corporate bodies like google, Sky, Disney and the Financial Times issuing a panicked letter to the government worried about the kind of bathroom bill which almost bankrupted North Carolina. So they've been looking at ways to try and show they are shitting on trans people without actually doing anything. Hence these guidelines, which have a whole section about how organisations going into schools musn't tell children they are born in the wrong body or that if they are gender nonconforming they are really the other sex, which no-one really did. They also highlight that RSE materials must be age appropriate, which was always pretty much the case. So not much is likely to change in terms of RSE content and in fact the guidelines still recommend Stonewall as a teaching resource to the dismay of those convinced they have an agenda to 'trans' children.
What's weird is they have also added all this other stuff about political groups, cancel culture and anti-capitalism to guidelines on who can teach sex education. And what's weirder is that
according to Schoolsweek the DfE have confirmed that the new guidelines are not statutory and as such schools have no legal duty to follow them. The far more benign guidelines which are still statutory and so which schools must follow can be found
here. The whole thing seems to have been an attempt to use guidelines to schools to generate some kind of culture war row in the media, possibly signal future intent, or test the mood, as well as try to indicate they were getting tough on cancel culture and other current bugbears of the right. So they've banned the Socialist Worker Party and Extinction Rebellion from teaching sex education, except they haven't even done that. This is a very strange way of doing Government, I suspect influenced by Trump but also possibly because Ministers like Truss sense the leadership is weak and are using dirty tricks to try and force policy direction.