Twitter is more of a platform imo, that has to have more permissive policies than a niche forum like HN. Benevolent dictatorships (especially opt-in ones) are great for smaller discussions. And people literally can go have their own discussion about celebrity gossip or whatever that would get killed on HN, in another forum.

Twitter is more like a utility, and if it wants to occupy that position it should be more open to content that people disagree with or don't like.