Sort of. The algorithm will boost or deprioritise posts being suggested. But any post, even those without any algorithmic boost, is visible to those who follow or show interest in the source, or those who seek them out.
As an analogy: someone puts up a poster. If someone else were to tear it down, you could call that censorship. And if someone else reprints the original poster and then goes around showing it to other members of the public, that's the equivalent of a boost from the Facebook algorithm.
When Facebook "deprioritises" a post, it's not tearing it down. It's still there, still visible to anyone looking for stuff nearby. All it's doing is refraining from doing all that extra stuff to spread it around.
More often than not, conspiracy theory bullshit is just conspiracy theory bullshit. Chemtrails, vaccines causing autism, disease-ridden produce being safer. All genuinely dangerous idiocy. I'd much prefer it be taken down, but if that's not possible, I at least don't want the algorithm actively promoting it.