My favorite Elie Wiesel quote:
"The opposite of love is not hate, it's indifference. The opposite of art is not ugliness, it's indifference. The opposite of faith is not heresy, it's indifference. And the opposite of life is not death, it's indifference."
We waste a lot of time and energy lumping those who actively hate people who are not like them with those who are simply indifferent to what others go through. Antagonists and psychopaths. Still not sure which is worse but they do present their own respective problems and require their own respective responses.
"So a middle school library should be an ideological free-for-all?"
The opposite that would be ideological indoctrination, so arguably, yes.