This assumes two things: firstly, that truth is itself an ultimate goal, and this pursuit overrides all other conflicts of rights; secondly, that ideas really do "fight it out in the open" and the long-run result of this process is desirable. It says nothing of what happens along the way (the "means"), it only cares about the ends.

Why is there a dichotomy between "[any and all ideas] fighting in the open" and "squashing hope of discovering many truths"? I also see no reason why this argument on the basis of truth would not justify restrictions on things which do not even foster dialogue on truth. The truth-value of 'hate speech' (if there is any truth value) is likely negligible compared to the same ideas expressed otherwise.

(On a more sensitive topic, the same algorithm that would ban "covid is just a flu" today would have also banned "face masks protect against covid" a year ago.)

It's not the opinions of anti-vaxers that are valuable, but potential other opinions which may look similar to the censor.