Even if you were right that debate on the shape of the earth had no benefit, forbidding it still wouldn't be science. Science is not coextensive with beneficial things.
If you assume that all opposing opinions come from flat-earthers and idiots that couldn't possibly be right about anything you will never even think about changing your opinion on anything. You'll continue to chat with other reddit yes-men and pat yourselves on the back about how you're all so right.
The upvote / downvote self-censorship system simply does not work for any serious discussions. It might be ok for sorting the snarkiest comment under an article but that's about it
I am not, in fact, denying you space for your views. I'm giving you the space for your views and explaining to you why they are incorrect.