But in that case it'd be easy for supporters of the law to argue it was just performative and clearly not really needed since they're otherwise accessible.
They are free to do that, but what of it? Sanctions and boycotts are "performative" in the same sense, and yet they continue being a popular tool to compel voters and politicians of other countries to act or refrain from acting in particular ways.
Wikipedia is a popular website that many people depend upon; denying access to UK users would not only create a massive inconvenience along with the temptation that it could be avoided if the law were rolled back, but would also encourage more UK users to adopt VPNs, which would subvert the law's effectivity along with that of a plethora of other authoritarian measures that the UK has in place.
I think the risk is that it becomes framed as extortion, and would cause some proportion of voters - who at least right after the OSA was put in place remained relatively in favour of elements of it (though the polls have been wildly flawed) - to double down.
Hence, I think a total block would be better than a partial block, because that can be framed as legitimately risk mitigation and would be a lot harder to attack.
That said, some pressure would be better than no pressure, so if the alternative is no block, I'd prefer a partial block.
That could drive users to LLM services to fill in the gaps. I know a lot of people who just use LLMs instead of good ol internet searches because they are that lazy.
