I think the “how” is pretty simple: the company is made up of people, the people define a set of principles, and adhere to them. They don’t have to accommodate everyone (and in my opinion, shouldn’t).
I think the hard part is doing this in the face of money. We have all seen how platforms allow awful things to exist because of the economic incentives to do so.
Not elected people, not respecting the most basic of constitutional principles. Not only that, but you can't enforce your "set of principles" on billion of tweets each hour of the day, not by people at least, so you defer to bots, which are incapable of discerning what is free speech. They can't apply your principles with the discernment of a human, they can't enforce what's legal or illegal, like they can't recognize copyrighted music from public domains ones.
I disagree with the constitutional angle. I do think enforcement is possible, it's really no different from enforcing the law IRL. I don't think having no terms and/or requiring private companies to have no terms is a better situation.
I think the hard part is doing this in the face of money. We have all seen how platforms allow awful things to exist because of the economic incentives to do so.