Exactly - the liability risk is huge, and relying on them not enforcing the law because they say they are 'unlikely' to on small sites is not a risk any sane person would take.

We don’t need to trust what they say, we just need to engage in a little critical thinking. What’s the benefit for Ofcom in pursuing tiny websites? There’s no political benefit, no financial benefit… the guidance from Ofcom reaffirms the natural conclusion.

There is no political benefit to imposing liability on any online forum operator for content posted by others?

Governments can abuse their power to silence speech it doesn't like. Governments can use agitators to develop pretext for legal action. Governments can make examples out of small-time defendants to send chilling effects. Governments can have prosecutors who may not be evil, but merely overzealous and harmful.

At the end, it is about a default to freedom of speech and content online (short of objectively illegal content) or a default to self-censorship and closing the gates on open forums.

Sorry, but that's foolish beyond belief. The law allows and probably mandates them to do so. You can pretend that's not what the law says but it clearly does. And it was written with intent and advice, so that's what the writers intended as well.

But if it's so simple, volunteer. Take on the criminal penalties yourself and perform the reviews.

Yeah exactly. And it will end up being a tool used to go against unfavoured groups.

Create a forum for supporters of (unfavourable person)? Sorry, your online complaints process isn't good enough, prison for you.

That's not what they are saying. What they are saying is that the law as written doesn't require the things that many small sites have been saying will be too expensive to comply with. The law as written only requires those things for large site and sites with elevated risk of certain harms. For most small sites any required changes will just be minor tweaks to things they are already doing.