@donquixotedelamancha are you a teacher or HT?
If so are you familiar with 'keeping children safe in education' it refers off to lot of other documents. One is internet safety. There might be no law on have a public rant on SM and linking that to your role as HT, but its conflict with what that document says that pupils should not be doing on SM if they dont want to end up under MASH radar.
So, your a pupil. You have a open public SM account and you, as a child talk about your school saying it's a unsafe space for children. Its public, someone sees it and flags it to safeguarding. Everyone says "bravo brave child, heres three rounds of hes a jolly good fellow". Nope. It gets taken seriously whether it's TRUE or not and MASH get a call.
So. Why is it ok for the head to do this? He works ultimately for the LA unless its private in which case this conversation is moot. The LA work for the Dfe. Dfe work for Gov. Your ranting about your top boss. SM isn't the place to bad mouth the CEO.
Also your telling your pupils to lock down SM whilst showing them its do as I say not as I do. That's two examples ofc the top of my head. I'm just a volunteer I have to know I couldnt do this in my role. I would be removed. So again why can the HT do things the govoners cant? We do the hiring and we also do the firing of the HT