Universities are also "speakers," with an independent mandate to teach, research, and pursue truth for the common good. And this requires taking sides.
I've found a pretty effective argument when dealing with right wingers at this point. I simply say that only one side is banning books and it's theirs, and I stick only to that. It's indefensible. They can try to twist it, say it's just protecting kids, and I will continue to say "Only the republicans are banning books". It's the end of discussion. Its shoving in their face that there is a clear line in the sand that republicans have crossed, and there is nothing they can say that would change that.
No we only need to protect them from liberal ideas! You see, nithing us more American than dying to a good honest made in the US bullet from a proud American gun, during second term at elementary school. But imagine if those kids would have read Marlon Bundo, a book about a male bunny that likes another male bunny as more than just friends, and everyone around being supportive?! That shit is dangerous!
So you can't think of any reason to ban books? Do you have any examples of a book that was banned recently by conservatives that clearly should not have been banned? What do you think about the following being in school libraries: page from Gender Queer (NSFW)?