The comments on the Mail site about this are good. Some of them calling for Bristol and Plymouth to be defunded. Perhaps the government will go down this road, perhaps not. It might be viewed as too close to no platforming or cancel culture.
However, surely there's some kind of legal and/or financial obligation from the Universities to the government, to spend money wisely? Spending money includes buildings, doesn't it?
The posters are not imparting a message based in law and as such they should be taken down. There are clear H&S obligations with toilet provision and that is the loop back to legal/financial duties to the government I'd be looking at if I were in government.