Why steem would ban 
Perhaps legal issues for management?
But then who 'owns' the steem chain? ie who is responsible, legally that is, for content uploaded?
As a user driven community, the concepts of free speech should apply.
Any individual or company who restricts that is working against the concepts.
The doc that are being released actually have nothing of any major significance so far, just a bunch of legal correspondence about who represents whoms, & who they are partnering with and how much their legal fees & costs are
Nothing indicates any national security breaches or imminent threats to any countries national security.
The 9-11 papers are of interest to a huge percentage of the public.
Why steem would take this account off line is a direct front to free speech.
Newspapers publish leaked and or stolen documents all the time.
The great thing about the steem chain is that there are many on ramps for publishers, which means it can't be controlled, especially by some individual / organisation that has vested interests.
Free speech is just that. Take it away and the next step is totalitarian, something we have suffered from with MSM propaganda.