Of course it's the UK government. You got a loicense to share that password, mate?
Probably the same in most of the world.
That tweet, in my not-in-any-way-legal-opinion says that Netflix allows password sharing.
As such, it is not a clear cut example of unauthorised access.
It's hard to imagine how an account holder could authorise you to access Netflix in a situation where Netflix explicitly communicates to you that such account sharing is forbidden.