* Two guys with pistols in a crowded bar: Attacker is favored.
* Trench warfare during WWI: Defender is favored.
* Nukes: Attacker is favored, although with the invention of nuclear submarines that could lurk under the ocean and offer credible retaliation even in the event of a devastating strike, the attacker became favored less.
In general equilibria where the defender is favored seem better. Venice became one of the wealthier cities in the medieval world because it was situated in a lagoon that gave it a strong defensive advantage. The Chinese philosopher Mozi was one of the first consequentialist philosophers; during the Warring States period his followers went around advancing the state of the art in defensive siege warfare tactics: http://www.tor.com/2015/02/09/let-me-tell-you-a-little-bit-a...
Notably, I'm told that computer security current favors attackers in most areas: http://lesswrong.com/lw/dq9/work_on_security_instead_of_frie... (BTW the author of this post is a potential Satoshi Nakamoto candidate and knows his stuff.)
In equilibria where the attacker is favored, the best solution is to have some kind of trusted central power with a monopoly on force that keeps the peace between everyone. That's what a modern state looks like. Even prisoners form their own semiformal governing structures, with designated ruling authorities, to deal with the fact that prison violence favors the attacker: http://www.econtalk.org/archives/2015/03/david_skarbek_o.htm...
Thought experiment: Let's say someone invents a personal force field that grants immunity to fists and bullets. In this world you can imagine that the need for a police force, and therefore the central state authority that manages the use of this police force, lessens considerably. The enforcement powers available to a central government also lessen considerably.
This is somewhat similar to the situation with online communities. We don't have a central structure governing discussions on the web because online communities favor the defender. It's relatively easy to ban users based on their IP address or simply lock new users out of your forum entirely and therebye keep the troll mobs out. Hence the internet gives us something like Scott Alexander's idea of "Archipelago" where people get to be a part of the community they want (and deserve): http://slatestarcodex.com/2014/06/07/archipelago-and-atomic-... Note the work done by the word "archipelago" which implies islands that are easy to defend and hard to attack (like Venice).
Let's assume that superintelligent AI, when weaponized, shoves us into an entirely new and unexplored conflict equilibrium.
If the new equilibrium favors defense we'd like to give everyone AIs so they can create their own atomic communities. If only a few people have AIs, they might be able to monopolize AI tech and prevent anyone else from getting one, though the info could leak eventually.
If the new equilibrium favors offense we'd like to keep AIs in the hands of a small set of trusted, well-designed institutions--the same way we treat nuclear weapons. It could be that at the highest level of technological development, physics overwhelmingly favors offense. If everyone has AIs there's the possibility of destructive anarchy. In this world, research on the design of trustworthy, robust, inclusive institutions (to manage a monopoly on AI-created power) could be seen as AI safety research.
The great filter http://waitbutwhy.com/2014/05/fermi-paradox.html weakly suggests that the new equilibrium favors offense. If the new equilibrium favors defense, even the "worst case scenario" autocratic regimes would have had plenty of time to colonize the galaxy by now. If the new equilibrium favors offense, it's entirely possible that civs reaching the superintelligent AI stage always destroy themselves in destructive anarchy and go no further. But the great filter is a very complicated topic and this line of reasoning has caveats, e.g. see http://lesswrong.com/lw/m2x/resolving_the_fermi_paradox_new_...
Anyway this entire comment is basically spitballing... point is that if $1B+ is going to be spent on this project, I would like to see at least a fraction of this capital go towards hammering issues like these out. (It'd be cool to set up an institute devoted to studying the great filter for instance.) As Enrico Fermi said:
"History of science and technology has consistently taught us that scientific advances in basic understanding have sooner or later led to technical and industrial applications that have revolutionized our way of life... What is less certain, and what we all fervently hope, is that man will soon grow sufficiently adult to make good use of the powers that he acquires over nature."
And I'm slightly worried that by virtue of choosing the name OpenAI, the team has committed themselves to a particular path without fully thinking it through.