It wasn't closed last I checked (I don't follow reddit closely anymore). It's off the r/all page unless you apply filters. You can still access it at will if you know where to find it, it just doesn't pollute the frontpage anymore with its bot-assisted mass upvote of shitposting and bullshit, which was against the site's rules.
And there wasn't any discussion going on. Like most zealous subreddits, anyone who didn't toe the party line was mass downvoted and booted almost immediately. The subreddit wasn't ''silenced'' or ''banned'' (like r/alt-right was), they broke the rules and got slapped for it.
And at the risk of repeating myself; they are basically the last people on the internet who have any right to take the moral high ground here. They shat on free speech every single day with reckless abandon to have their safe space. Now they are just angry to have a taste of their own medicine.