It seems like a function of universities can/should be to filter out as many terrible ideas as possible....
Should we apply that principal to the library as well? Remove all the books with "terrible ideas"?
Same principle. I wouldn't advise wasting library funds on creationist textbooks, and I would recommend removing factually-inaccurate items from the non-fiction section.
But books are still a better place to hedge against the possibility that my idea-quality-metric is seriously broken, as a matter of economics. I'd still prioritize good ideas over terrible in book acquisition, but with an added component for diversity as judged by my quality metric (aiming for a long-tail distribution as judged by my personal idea-quality metric, for example). You can have ...
Related: Heuristics for Evaluating the Soundness of the Academic Mainstream, Admitting to Bias, The Ideological Turing Test