Why couldn't twitter say "we will delete any tweets that are critical about a certain person"? is there a law against that? is it morally wrong? It seems that

Why couldn't twitter say "we will delete any tweets that are critical about a certain person"? is there a law against that? is it morally wrong? It seems that if they wanted, they could say "we want Candidate X to win and will do whatever is in our power to make that happen". What would people do then? Equal time laws don't apply to twitter any more than they do to your blog. There is nothing stopping them from acts of outright censorship for any purpose they choose. The nature of social networks is that some platforms will have more users and exponentially more value than others, so it seems like there isn't choice in the market. We as a society have to decide if "having the most users" is equivalent to the physical infrastructure connections that currently designate utilities and monopolies. Having to tolerate political censorship is an obvious tradeoff. But if we go full Section 230, we could wind up with a situation where US companies are hobbled and replaced by foreign competitors. Or where American companies stop improving their service because they enjoy the advantages of a utility/monopoly. It's actually a new and difficult social question that requires a lot of thought. I think I know what side I'm on.