So if the Hacker hacks the SSO system.....
The article headline asks how to tell hacker vs. user but does not answer the question. How does SSO do that?
It would be good to mention when the author of the article works for one of the companies mentioned in the article.
To simultaneously talk about remote access, web site authentication, cloud, and enterprise SSO in one breath is terribly confusing.
You don't use SSO for enterprise remote access (it's SSO by definition), you don't expose your SSO and AD to your web apps, and most enterprise security people are not likely to extend their authentication services out through their firewall to their business partners.
Now if you're talking Cloud and SaaS, that's a whole different story. But in this case the whole app is 'outside the secruity perimeter' so putting the authentication out there is only logical.