I think we agree legally it’s fine, but I still disagree and think it’s ethically fine. Companies realize putting their point of contacts on third party services is risky and should be mitigating that.
Like a company should have their own email domain rather then Gmail. There are things you can digitally own, like the domain name itself because you purchase it and then have a contract with it.
If Twitter acted as a service where you buy your profile and make an agreement, that would be unethical at that point, and also illegal. Twitter users shouldn’t be under the impression they perpetually own their account handle, they haven’t paid anything and simply claimed it through a signup or username change. That’s not comparable to say, buying a domain, where that would be extremely unethical and pretty sure illegal. Also impersonation is bit of a funny topic to bring up with Twitter right now lol, considering how messed up the verification is.
I would agree with you if social media services were treated as like a utility and usernames were contracted as such. Which I actually do wish was a thing, it’d be a much healthier ecosystem with much stronger protections. But that’s a different topic.